Snapshot User s Manual (Installation and Operation Guide for Linux)

Transcription

1 NEC Storage Software Snapshot User s Manual (Installation and Operation Guide for Linux) IS035-17E

2 NEC Corporation No part of the contents of this book may be reproduced or transmitted in any form without permission of NEC Corporation. The contents of this book may be modified without notice in the future.

3 Preface This manual describes how to use the snapshot function provided by NEC Storage DynamicSnapVolume and NEC Storage ControlCommand. The snapshot function consists of the snapshot creation function provided in NEC Storage series disk array subsystem and software to manage and operate it. It utilizes snapshot to make business operation more effective. This manual describes comprehensive explanation of the snapshot function and how to operate the function from software. The following manuals describe the procedure for using the snapshot function from an application server and how to operate the function in detail. NEC Storage Software Snapshot User s Manual (Function Guide) (IS030): This manual describes comprehensive explanation of the snapshot function and how to operate the function from software. NEC Storage Software Snapshot User s Manual (Installation and Operation Guide for Windows) (IS031): This manual describes how to install and operate the snapshot function on Windows OS. NEC Storage Software ControlCommand Command Reference (IS041): This manual describes command syntax and how to operate commands that operates the snapshot function from a command line. NEC Storage Software Messages Handbook (IS010): This manual describes messages output by the NEC Storage series software. This manual also includes messages output by the snapshot function. Refer to the NEC Storage Software Manual Guide (IS901) for the overview of NEC Storage and the related manuals. Remarks 1. This manual explains functions implemented by the following program products: NEC Storage Manager and NEC Storage BaseProduct NEC Storage ControlCommand NEC Storage DynamicSnapVolume NEC Storage DynamicDataReplication NEC Storage RemoteDataReplication 2. This manual is applicable to the program products of the following versions: NEC Storage Manager Ver7.4 or later NEC Storage BaseProduct Ver7.4 or later NEC Storage ControlCommand Ver7.4 or later

4 3. The NEC Storage Manager is referred to as ism or Storage Manager in this manual unless clearly specified. Also, the following terms refer to the corresponding NEC Storage software products. Term NEC Storage Software Product AccessControl ControlCommand DynamicDataReplication or DDR DynamicSnapVolume PathManager PerformanceMonitor RemoteDataReplication or RDR NEC Storage AccessControl NEC Storage ControlCommand (Note) NEC Storage DynamicDataReplication NEC Storage DynamicSnapVolume NEC Storage PathManager NEC Storage PerformanceMonitor NEC Storage RemoteDataReplication Note: NEC Storage ControlCommand is a program product that has integrated the following five functions. ReplicationControl SnapControl ReplicationControl/DisasterRecovery ProtectControl PowerControl 4. The NEC Storage series disk array subsystem is referred to as a disk array in this manual unless clearly specified. Also, the following terms refer to the corresponding NEC Storage hardware products. Term NEC Storage Hardware Product D series Sxxx or Sxxxx * xxx and xxxx represent the model number. NEC Storage D series NEC Storage Sxxx or NEC Storage Sxxxx 5. The following terms in this manual refer to the NEC Storage software manuals. Term NEC Storage Software Manual User s Manual (UNIX) Configuration Setting Tool User s Manual (GUI) Messages Handbook NEC Storage Software NEC Storage Manager User s Manual (UNIX) (IS001) NEC Storage Software Configuration Setting Tool User s Manual (GUI) (IS007) NEC Storage Software Messages Handbook (IS010) Snapshot User s Manual (Function Guide) ControlCommand Command Reference PathManager User s Manual (Linux) NEC Storage Software Snapshot User s Manual (Function Guide) (IS030) NEC Storage Software ControlCommand Command Reference (IS041) NEC Storage Software PathManager User s Manual (Linux) (IS202) 6. Trademarks and registered trademarks UNIX is a registered trademark of The Open Group in the United States and other countries. VERITAS, VxVM, VxFS, NetBackup, VERITAS Volume Manager, VERITAS File System, and VERITAS NetBackup are trademarks or registered trademarks of Symantec Corporation or its affiliates in the United States and other countries. Linux is a trademark or registered trademark of Mr. Linus Torvalds in the United States and other countries.

5 Other product names and company names, etc. are registered trademarks or trademarks of the associated companies. 7. In this document, the capacity is calculated based on units of 1024 (for example 1 KB = 1024 bytes) unless otherwise specified. 8. In this document, matters to which careful attention needs to be paid will be described as follows: Be sure to observe the instructions. If the indications are ignored and the system is improperly operated, settings which have been already made might be affected. Type of Indication Type Description Describes contents which require users to pay special attention for operation. Describes information about restrictions on operation. 1st Edition in December th Edition in March 2012

6 Contents Chapter 1 Installation Procedure Installation Procedure System Configuration Hardware Configuration Software Configuration Software Installation ism Snapshot Management SnapControl Disk Array Configuration Product License Unlocking Binding a Logical Disk (LD) Settings of Disk Array Name, Logical Disk Name, and Port Name Binding the Snapshot Reserve Area Binding a Snapshot-Volume Binding a Link-Volume Access Control Setting Control Volume Setting Volume List Creation Preparing Volume...16 Chapter 2 Operation and Maintenance Logical Fault and Physical Fault Operations Example of Backup Operation Example of Restoring Business Volume Data Data Restoration without Using Snapshot Function Data Restoration Using Snapshot Function (Logical Fault) Data Restoration Using Snapshot Function (Physical Fault) Example of Secondary Use of Snapshots Measures for Errors Snapshot Fault ism Server or Client Fault Abnormal End of SnapControl Invalid Product Collecting Information of Error of Unknown Cause Operations when the Configuration is Changed Conditions Requiring Volume List Update Updating Volume List...47 Chapter 3 Notes Snapshot Access Restriction Selection Access Right Settings on Files in Volumes Volume Operations of LVM and VxVM Using LVM and VxVM Operations for LVM Volume Group Operations for VxVM Disk Group Using the Special File for PathManager Changing Configuration Using Access Control Restarting Server Connecting to LV (SV) Control Volume Management and Operations of Snapshot Linking with Replication Function Recommended Configuration for SATA Disk Model...60 Index...61 i

7 Chapter 1 Installation Procedure Chapter 1 Installation Procedure This chapter describes the system installation procedures showing an example of a tape backup system IInstallllatiion Procedure Installation tasks are outlined below. For details on each task, refer to the associated sections. Works followed by (*) mark are necessary for all servers installing SnapControl (including standby servers in cluster configuration). 1. Determining the system configuration Select necessary hardware configuration Select necessary software configuration Hardware Configuration Software Configuration 2. Installing software (*) Install/Uninstall/Update ism Install/Uninstall/Update SnapControl ism Snapshot Management SnapControl 3. Determining the disk array configuration Unlock the product license Bind a necessary logical disk (LD) Assign an identification name to the management target hardware Bind a snapshot-volume Product License Unlocking Binding a Logical Disk (LD) Settings of Disk Array Name, Logical Disk Name, and Port Name Binding the Snapshot Reserve Area Binding a Snapshot-Volume Set Access Controls according to the connection state Binding a Link-Volume Access Control Setting 4. Setting a control volume (*) Only when a control volume is used 1.5 Control Volume Setting 5. Creating the volume list (*) 1.6 Volume List Creation 6. Preparing volumes (*) 1.7 Preparing Volume 1

8 Chapter 1 Installation Procedure 1..2 System Confiiguratiion Hardware Conffiigurattiion Select hardware components according to the business conditions, requirements, disk capacity, and so forth. Figure 1-1 shows an example of hardware configuration. Client Management Server LAN Application Server Backup Server Tape Device (FC-switch) Disk Array Figure 1-1 Hardware Configuration Example To utilize the snapshot function most efficiently, it is better to separate application servers, which process tasks, from backup servers. Thus, tape backup operation gives no additional load to application servers. In the environment using VxVM, it is not possible to operate BV and a snapshot on the same server. Therefore, the application server used for operations should be different from the backup server. In the environment using LVM, it is possible to operate both on the same server, but you need to take care about the procedures for operations. Though the business or backup server may also be used as a management server, using a specific management server is recommended. Use of LAN connection is strongly recommended for connection with disk array. Connect the path of individual servers, to be connected to the disk array, to the port of different directors of the disk array, limiting the servers to be accessed by Access Control. 2

9 Chapter 1 Installation Procedure Soffttware Conffiigurattiion Select software to be used according to the hardware components, operating conditions, etc. Figure 1-2 shows a software configuration example. Client Management Server Storage Manager PerformanceMonitor LAN Application Server Backup Server ControlCommand (SnapControl) ControlCommand (SnapControl) Backup Software Tape Device (FC-switch) Disk Array DynamicSnapVolume AccessControl Figure 1-2 Software Configuration Example Install the business application software in the application server. Install the backup software in the backup server. Install the management software in the management server. Install the ism in the management server. Install the SnapControl in the business and backup servers. Install the DynamicSnapVolume in the disk array. From the server where the ism is installed, the ism snapshot management functions can be executed for disk arrays where the DynamicSnapVolume has been installed once installation is completed. 3

10 Chapter 1 Installation Procedure 1..3 Software IInstallllatiion iism Snapshott Managementt (1) Operating Environment Snapshot Management (Server) The snapshot management (server) is included in the ism. For details on the operating environment, refer to the installation guide attached to the ism. Snapshot Management (GUI) The snapshot management (GUI) is included in the ism Client. For details on the operating environment, refer to the installation guide attached to the ism. (2) Installation ism Server Installation When you install the ism, the snapshot management (server) of the ism server is also installed. For details on the installation procedure, refer to the installation guide attached to the ism. ism Server Setting Create an environment definition file and the environment according to the installation guide attached to the ism. Snapshot Management (GUI) Installation For details on the installation procedure, refer to the installation guide attached to the ism. (3) Uninstallation ism Server Uninstallation For details on the uninstallation procedure, refer to the installation guide attached to the ism. Snapshot Management (GUI) Uninstallation For details on the uninstallation procedure, refer to the installation guide attached to the ism. (4) Update ism Server Update To update the ism software, uninstall the existing software, and then install the new software. For details on the installation and uninstallation procedure, refer to the installation guide attached to the ism. 4

11 Chapter 1 Installation Procedure SnapConttroll (1) Operating Environment Operating system and linkage software For details on the OSs supporting this software and the linkage software that can be used in conjunction with this software, refer to the installation guide attached to this software. Required disk free space For details on the disk free space required to install this software, refer to the installation guide attached to this software. Note that this software is installed under the /opt and /etc directories. Required memory For details on the memory capacity required to install this software, refer to the installation guide attached to this software. (2) Installation For details on the installation procedure, refer to the installation guide attached to this software. (3) Setting Operating Environment You can set various types of operations when executing a command by using the environment variables. For details on the environment variables, refer to the ControlCommand Command Reference. (4) Uninstallation For details on the uninstallation procedure, refer to the installation guide attached to this software. (5) Update To update the SnapControl software, uninstall the existing software, and then install the new software. For the details of the installation and uninstallation procedure, refer to the installation guide attached to this software. 5

12 Chapter 1 Installation Procedure 1..4 Diisk Array Confiiguratiion For the disk array to be connected, determine the configuration for using the snapshot Productt Liicense Unllockiing To use the DynamicSnapVolume, you must unlock the product license set in the disk array. To unlock the license, you must purchase the corresponding products for the capacity category equal to or greater than the total physical capacity of the disk array. At starting up, the snapshot management and SnapControl check the license status of the products and check whether they are available. If the total capacity of the physical disk exceeds the product s specified capacity because physical disks are added to the disk array system, no additional snapshots can be constructed. However, operations for the constructed snapshot are available. For details on the operation procedure, refer to the Configuration Setting Tool User s Manual (GUI) Biindiing a Logiicall Diisk ((LD)) When you bind a snapshot-volume, consider the following points to determine a logical disk configuration in a disk array. Pool and logical disk Save BV either in the basic pool or the dynamic pool. Save SV and LV in the dynamic pool. Save SRA (SDV) in the pool where SV is to be created. BV and SV can be created in different pools. Create LV in the same pool as SV. Save all SVs that were set in the same BV in the same pool. Save a control volume (CV) either in the basic pool or the dynamic pool. Then, bind a volume used for operations and a control volume used for operations. Figure 1-3 shows a construction example of the system where a dedicated server performs backup operation of a volume to be used by a application server using snapshots. For details on the operation procedure, refer to the Configuration Setting Tool User s Manual (GUI). 6

13 Chapter 1 Installation Procedure Application Server Backup Server CV BV SV SV SV SV LV BV SV SV SV SV SRA LV BV SV SV LV BV SV SV LV SRA BV: Base-volume SV: Snapshot-volume SRA: Snapshot reserve area LV: Link-volume : Pool CV: Control volume : Access Control Figure 1-3 Configuration Example of Logical Disk 7

14 Chapter 1 Installation Procedure Settttiings off Diisk Array Name,, Logiicall Diisk Name,, and Portt Name You can assign identification names to hardware components managed by the ism. Identification names can be given to the following items: Disk array subsystem name Logical disk names (plus OS type) Port name It is better to set the disk array subsystem names, port names, and logical disk names according to the operating conditions and server connection conditions. When you use the snapshot function, you do not need to note disk array names and port names. For the OS type of a logical disk, you need to note the following. The OS type of SDV cannot be set. The OS type of BV must be appropriate for the supporting platform. The OS types of SV and LV are set in the same type as BV at volume binding. After creation of the generation, you cannot change the OS types of BV and SV/LV. These settings are performed from an ism client. For details on the operation procedure, refer to the User s Manual (UNIX). Table 1-1 Example of Disk Array Name Setting Disk Array Subsystem Disk Array Subsystem Name S2800 Remark 1: Tokyo_Customer_DataBase This is an example of setting a disk array name for administrating database of customers in Tokyo. Table 1-2 Setting Example of Port Names Director Number Port Number Port Name Connected Server 00h 00h DB_SECONDARY 01h 00h DB_PRIMARY 00h 01h BACKUP_PRIMARY 01h 01h BACKUP_SECONDARY Application server Backup server Remark 1: This is a setting example conforming to the connection configuration of servers. 8

15 Chapter 1 Installation Procedure Table 1-3 Example of Setting Logical Disk Names and OS Types LD No. OS Type Logical Disk Name Remarks 0000h DB_DATA_BV BV for DB data file 0001h DB_REDO1_BV BV for DB REDO file h DB_REDO2_BV BV for DB REDO file h DB_CTL_BV BV for DB control file 0004h DB_ARCHIVE_BV BV for DB archive file 0010h DB_DATA_SV SV for DB data file 0011h DB_REDO1_SV SV for DB REDO file h DB_REDO2_SV SV for DB REDO file 2 LX 0013h DB_CTL_SV SV for DB control file 0014h DB_ARCHIVE_SV SV for DB archive file 0020h DB_DATA_LV LV for DB_DATA_SV access 0021h DB_REDO1_LV LV for DB_REDO1_SV access 0022h DB_REDO2_LV LV for DB_REDO2_SV access 0023h DB_CTL_LV LV for DB_CTL_SV access 0024h DB_ARCHIVE_LV LV for DB_ARCHIVE_SV access 002ah BACKUP_CV Control volume 0100h (Blank) SDV1 Snapshot data volume Remark 1: Remark 2: Set the OS type to LX, the default value for the LX systems (excluding snapshot data volumes). This example shows logical disk names conforming to the database configuration. Access Control is necessary for a system in which the snapshot function is installed. Before performing the following operations, enable Access Control setting. In addition, Access Control setting needs to be performed for volumes that have already been used for other operations Biindiing tthe Snapshott Reserve Area The snapshot reserve area (SRA) must be prepared in the pool where a snapshot-volume (SV) is created. The snapshot reserve area is bound by the configuration setting function of the ism client. For details on the construction procedure, refer to the Snapshot User s Manual (Function Guide). 9

16 Chapter 1 Installation Procedure Biindiing a Snapshott--Vollume To bind a snapshot-volume (SV), specify the logical disk (BV) from which a snapshot is to be replicated and the necessary number of generations. A snapshot-volume is bound by the configuration setting function of the ism client. For details on the binding procedure, refer to the Snapshot User s Manual (Function Guide) Biindiing a Liink--Vollume To bind a link-volume (LV), specify a base-volume (BV) in advance. A link-volume (LV) is bound by the configuration setting function of the ism client. For details on the binding procedure, refer to the Snapshot User s Manual (Function Guide) Access Conttroll Settttiing Usually, you need to set the system with snapshots so that the created snapshot images cannot be referenced by an application server that uses BV to prevent a wrong update to a volume or a wrong modification of the disk configuration on an application server. Therefore, to use snapshots, you need to limit logical disks that can be accessed from a server by using Access Control. To use snapshots, take note the following points and set Access Control. Setting Access Control Connect BV to an application server. Connect LV to the server that accesses SV. Do not connect SV and SRA (SDV) to a server. Connect CV to the server to which SV (LV) is assigned. Before introducing servers, you must determine the server connection modes and design Access Control settings. Access Control can be set for individual ports or WWNs. After setting Access Control, restart the system so that each server can recognize the volume. Setting for Access Controls requires purchasing the AccessControl. For details on the setting procedures, refer to the Configuration Setting Tool User s Manual (GUI). 10

17 Chapter 1 Installation Procedure 1..5 Controll Vollume Settiing A control volume is used when a server issues control I/O to the relevant disk array. Register one logical disk for each disk array as the volume for issuing I/O to that disk array in the volume list. The use of a control volume has the following effects. A control volume is necessary in the backup server not connected to BV. Operation is possible even when an LV connected to the server or a replication-volume (RV) for the data replication function cannot be accessed from the server (operating system) due to a snapshot or data replication operation. You can specify BV to view the information from the backup server not connected to BV. Logical disks that can be operated from a server by using a control volume are those that are allowed to access the server by the Access Control of a disk array or those that are paired with the logical disks that are allowed to access the server. For details on a control volume, refer to 3.5 Control Volume also. RV, or a base-volume (BV) and link-volume (LV) for the snapshot function cannot be registered as a control volume because it may enter the Not Ready state during operation. The purpose (attribute) of logical disks built as control volumes can be identified with the following disk array series. D series When the logical disk information is displayed by the ism client (and so on) for disk arrays on which the purpose (attribute) of a control volume can be identified, the identification information indicating the control volume as a logical disk purpose (attribute) is displayed. 11

18 Chapter 1 Installation Procedure The control volume setting procedure differs depending on the disk array functions as shown below. (1) Disk arrays identifying the control volume attribute Create or update the volume list when the logical disk built as a control volume is connected to the server and recognized as a disk by the system. The disk array identifies the logical disk having the control volume attribute from the logical disks connected to the server and automatically registers it in the volume list. To create or update the volume list, refer to 1.6 Volume List Creation. After creating or updating the volume list, list the control volumes using the ismvollist command to check that the control volume has been successfully registered in the volume list. ismvollist -ctl (2) Other disk arrays It is necessary to select the control volume from the logical disks connected to the server, and describe it in the control volume definition file on the server for definition. Describe the logical disk number (LDN) and disk array name of the logical disk to be used as a control volume in the control volume definition file. You can check the information on the logical disk by using the ismrc_ldlist command. This information includes the list of disk arrays connected to the server, disk array names, list of logical disks in each disk array, and logical disk numbers. - To display the list of disk arrays and disk array names ismrc_ldlist -d - To display the list of logical disks in the disk arrays and the logical disk information ismrc_ldlist -de Disk array name Select and describe one logical disk for each disk array. If you describe multiple logical disks in the same disk array, the information on the first one becomes valid and the information on the second and subsequent ones is ignored. [File location and file name] /etc/ismrpl/ctlvol.conf [Format] Describe the logical disk numbers and disk array names of all the control volumes used in the relevant server. Write the set of logical disk number and disk array name corresponding to each control volume on a single line by delimiting these sets with line feed. The logical disk number on each line should be in hexadecimal. Delimit the logical disk number and disk array name with a space or tab character. On each line, the text after the pound symbol (#) is regarded as a comment and ignored. 12

19 Chapter 1 Installation Procedure A description example is shown below. # ControlVolumes # LDN Disk Array Name 002a Tokyo_Customer_DataBase Rules Start description at the first column on the line. Use the line feed to delimit records. One record should be up to 1,024 characters (1-byte). One record describes one control volume. The text from the pound symbol (#) to the end of the record is regarded as a comment. Control Volume Registration You should have updated the volume list to reflect the setting information described in the control volume definition file. To create or update the volume list, refer to 1.6 Volume List Creation. After creating or updating the volume list, list the control volumes by using the ismvollist command to check that the control volume has been successfully registered in the volume list. ismvollist -ctl 13

20 Chapter 1 Installation Procedure 1..6 Vollume Liist Creatiion Creation of a volume list is required before using snapshot operation command. A volume list is created by the ismvollist command with the -r option specified. Create a volume list with the appropriate user privilege. The following command line shows an example to create a volume list with the ismvollist command. ismvollist -r Upon successful creation of a volume list, the following message appears: ism11100: Command has completed successfully. If creation of a volume list fails, execution of snapshot operation commands is disabled. After troubleshooting the problem in accordance with an error message or with operation error tracing, create a volume list again. If the ism server is running on the same server, it is required to exit ism before creating a volume list. Create a volume list in the following states. - The path between the disk array and the server is normally connected. - The logical disk in the disk array is recognized as a server (OS) disk device. - The volume in the disk is recognized by the server (OS). Execute the following operation before creating a volume list if you use a control volume in the disk array with which the control volume attribute cannot be identified. - Define the logical disk to be used as the control volume in advance in the control volume definition file. 14

21 Chapter 1 Installation Procedure To successfully register volume information in the volume list, create a volume list in the following states. - Pairs are separated when the RV is connected to the server. - The link-volume (LV) and snapshot-volume (SV) are linked when the LV in the snapshot function is connected to the server. The base-volume (BV) and LV are not linked when the BV is connected to the server. - Protected data is readable when the logical disk for which the data retention function is applied is connected to the server. - The volume is in the In use state and accessible when the logical disk for which the power saving function is applied is connected to the server. - The link path between disk arrays is normal when the RemoteDataReplication is configured for the disk array. After successfully creating a volume list, display the information registered in the volume list to check that the items to be used such as logical disks and special file names are all registered correctly. Once the volume list is successfully created, that information is maintained for operation. It is not necessary to update the volume list during operation. However, if the disk array, server (OS) volume, or other configuration is changed, it is required to recreate the volume list to reflect the new information. Note that an error or inconsistency may occur at execution of snapshot operation command unless the volume list is updated. For details on how to update the volume list when the configuration is changed, refer to 2.4 Operations when the Configuration is Changed. 15

22 Chapter 1 Installation Procedure 1..7 Prepariing Vollume This section describes volume preparation you have to make before starting operation. (1) When using LVM This section describes volume binding and necessary preparations when you use LVM in a non-cluster system. LVM Configuration Bind the volume group and logical volume on the application server. If they are already bound, this task is not necessary. For details on how to bind the LVM, refer to the relevant manuals. For notes on binding, also refer to Chapter 3 Notes. The following procedure assumes that the LVM logical volume has the configuration shown in Figure 1-4. Logical Disk BV 2 GB /dev/sda Volume Group (Disk Pool) dev/vg01 Logical Volume /dev/vg01/lvol Figure 1-4 LVM Configuration 16

23 Chapter 1 Installation Procedure Step 1. Creating a file system (applicaiton server) Bind a file system used for applications if necessary. Bind a file system by entering the following. In this example, ext3 is used as a file system. mkfs -t ext3 /dev/vg01/lvol Step 2. Creating a generation (application server) Check that a snapshot generation and link-volume have been created for BV. Here, create a generation so that BV data will be replicated as shown in Figure 1-5. When creating a generation, you must specify SVs disk so that they have one-to-one correspondence with logical disks making up the volume group. LV Logical Disk BV SV (lv001) /dev/sda /dev/sdb Volume Group (Disk Pool) dev/vg01 dev/vg01 Logical Disk Logical Volume /dev/vg01/lvol /dev/vg01/lvol Figure 1-5 Image of LVM Disk Generation Creation and Replication Step 3. Saving the BV volume group setting information Save the BV volume group setting information. vgcfgbackup /dev/vg01 17

24 Chapter 1 Installation Procedure (2) When using VxVM This section describes volume binding and necessary preparations when you use VxVM. VxVM Configuration The VxVM logical volume has the configuration shown in Figure 1-6. For notes on binding, also refer to Chapter 3 Notes. Logical Disk Logical Volume BV 2 GB /dev/sda Volume Manager Disk (VM Disk) disk01 Disk Group (Group of VM Disks) dg01 Volume vol1 Figure 1-6 VxVM Configuration Step 1. Creating a file system (application server) Bind a file system used for applications if necessary. Bind a file system by entering the following. In this example, VxFS is used as a file system. mkfs -t vxfs /dev/vx/dsk/dg01/vol1 Step 2. Creating a generation (application server) Check that a snapshot generation and link-volume have been created for BV. Here, create a generation so that BV data will be replicated as shown in Figure 1-7. When creating a generation, you must specify SVs disk so that they have one-to-one correspondence with logical disks making up the disk group. 18

25 Chapter 1 Installation Procedure Logical Disk BV SV LV (lv001) /dev/sda /dev/sdb Volume Manager Disk (VM Disk) disk01 disk01 Disk Group (Group of VM Disks) dg01 dg01 Volume vol1 vol1 Figure 1-7 Image of VxVM Disk Generation Creation and Replication Step 3. Setting a link of a volume (backup server) Set a link from LV to SV for which a snapshot was created in Step 2. In this example, assume that a link is set from link-volume lv001 to logical disk name sv001_1. ismsc_link -lv lv001 -lvflg -sv sv001_1 -svflg ld Step 4. Writing data to a partition table (backup server) To make a backup server recognize partition information, use the fdisk command and others to write data to a partition table. To write data to a partition table using the fdisk command, execute the following. fdisk /dev/sdb Select "w" subcommand from the displayed menu, and write data. Step 5. Recognizing the device path (backup server) To make VxVM recognize the device path, execute the following command. vxdctl enable 19

26 Chapter 1 Installation Procedure Step 6. Setting LV (SV) offline (backup server) Set LV (SV) disk status offline. vxdisk offline sdb Step 7. Unlinking a volume (backup server) Release a link to SV set in Step 3. In this example, assume that a link set from link-volume lv001 to logical disk name sv001_1 is released. ismsc_unlink -lv lv001 -lvflg ld -sv sv001_1 -svflg ld About recognition of partition information When a server was made to recognize partition information using a command such as fdisk, restarting is necessary. After restarting, the created partition becomes available. (3) Example where Volume Management is Not Performed This section describes volume binding and necessary preparations when you do not use any volume management software such as LVM or VxVM and perform volume management. Step 1. Creating a file system (application server) Create a file system used for applications if necessary. Create a file system by entering the following. In this example, ext3 is used as a file system in an environment that has PathManager installed. mkfs -t ext3 /dev/dda Step 2. Creating a generation (application server) Check that a snapshot generation and link-volume have been created for BV. BV SV LV (lv001) /dev/sda /dev/sdb Figure 1-8 Image of Generation Creation and Replication of Logical Disk without Volume Management 20

27 Chapter 2 Operation and Maintenance Chapter 2 Operation and Maintenance This chapter describes an operation example using the snapshot function, snapshot operation, and troubleshooting for faults that may occur during operations Logiicall Faullt and Physiicall Faullt A replication volume created by the snapshot function has the following features: It is a virtual volume holding only the differential data block with a copy-source volume. It shares the data block other than the difference with a copy-source volume. Therefore, the snapshot is affected differently depending on the fault type. Logical Fault It indicates a fault that unintended and invalid data is written to the business volume due to an operation error or an application fault. Overwriting data or deleting necessary files mistakenly, garbled data due to application fault etc. are the cases. A logical fault is caused not by hardware fault but by human error or software problem. When a logical fault occurs in the copy-source business volume, copy-destination snapshot is not influenced. You can restore the business volume by using the snapshot created before the fault occurred. Physical Fault It indicates a fault that data of the business volume is destroyed due to a hardware fault and becomes unavailable. It requires physical restoration such as hardware exchange. When a physical fault occurs in the copy-source business volume and data is destroyed, copy-destination snapshot also becomes unavailable. Volumes in the disk array are in RAID configuration, and data is not destroyed unless multiple faults occur. In case of physical fault, however, you must restore data from other media, not from snapshots. 21

28 Chapter 2 Operation and Maintenance 2..2 Operatiions Examplle off Backup Operattiion This section describes an example of static point backup operation using the snapshot function. (1) Overview The snapshot of data (data file) in the business volume (BV) used in operation is created. Then, it is saved to the tape by using backup software. Assume that the backup environment has the configuration shown in Figure 2-1. Also assume that LV used for access from SV (the first generation) and a backup server has been constructed and operation has started in volumes. It is assumed that the following information is given to each volume. BV: Logical disk name (bv001) SV: Logical disk name (sv001_01) LV: Logical disk name (lv001) Application Server Backup Server Tape Device Backup Software BV SV LV Business Volume Snapshot Figure 2-1 Example of Backup Operation 22

29 Chapter 2 Operation and Maintenance Work flow of backup operation example <<Application server>> <<Backup server>> Step 1. Deleting an old snapshot Step 2. Terminating applications (1) Terminating applications (2) Unmounting BV (3) Deactivating the volume group Step 3. Creating a snapshot Step 4. Setting SV guard Step 5. Restarting applications (1) Activating the volume group (2) Mounting BV (3) Restarting applications Step 6. Setting a link between LV and SV Step 7. Mounting LV (SV) (1) Activating the volume group (2) Mounting LV (SV) Step 8. Executing backup Step 9. Unmounting LV (1) Unmounting LV (SV) (2) Deactivating the volume group Step 10. Releasing a link between LV and SV Step 11. Canceling SV guard 23

30 Chapter 2 Operation and Maintenance (2) Operation procedure Step 1. Deleting an old snapshot (application server) It may take some time to delete a snapshot depending on the differential quantity of volumes. Therefore, before terminating operation, delete the generation for which a snapshot is to be created. If you use a snapshot cyclically, use the following command to delete a snapshot. ismsc_delete -bv bv001 -bvflg ld -auto Step 2. Terminating applications (application server) You have to create a perfect static point of BV data before creating a snapshot. This is for completely writing all the data remaining in the cache to the disk. This task also intends to prevent I/O processing to/from the logical volume (file system) in order to maintain the data consistency between BV and snapshot. The procedure is shown below. (1) Terminating applications Terminate the operations and applications that use BV. (2) Unmounting BV Unmount the logical volume used as a file system. umount /bvfs1 (3) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the BV volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the BV disk group. vxdg deport dg01 Step 3. Creating a snapshot (application server) Create a snapshot on SV and enable operation to be restarted. ismsc_create -bv bv001 -bvflg ld -cyclic Step 4. Setting SV guard (application server) Set SV guard classification to prevent a snapshot from being overwritten by cyclic use while waiting for the backup to be completed to a tape or other device. ismsc_svguard -bv bv001 -bvflg ld -sv.-1 -svflg relgen -mode set 24

31 Chapter 2 Operation and Maintenance Step 5. Restarting applications (application server) Restart BV as the business volume. (1) Activating the volume group or importing the disk group If you use LVM, activate the BV volume group. vgchange -a y /dev/vg01 If you use VxVM, import the BV disk group. vxdg import dg01 vxvol -g dg01 startall (2) Mounting BV If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /bvfs1 If you use VxVM, mount the VxVM logical volume. In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /bvfs1 (3) Restarting applications Restart the terminated operations (such as applications). Step 6. Setting a link between LV and SV (backup server) Link LV to SV to access a snapshot. Setting a link enables access to SV depending on the access restriction specified at link setting. ismsc_link -lv lv001 -lvflg ld -sv bv svflg ld.relgen * Hereafter, the snapshot linked to LV is referred to as LV (SV). Step 7. Mounting LV (SV) (backup server) (1) Activating the volume group or importing the disk group If you use LVM, activate the LV (SV) volume group. vgscan vgchange -a y /dev/vg01 If you use VxVM, import the LV (SV) disk group after setting the disks online. vxdisk online sdb vxdg -C import dg01 vxvol -g dg01 startall 25

32 Chapter 2 Operation and Maintenance (2) Mounting LV (SV) Mount LV (SV) (logical volume). If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /svfs1 If you use VxVM, mount the VxVM logical volume. In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /svfs1 Step 8. Executing backup (backup server) Back up the snapshot created in SV from LV to the tape or other devices using the backup software. Step 9. Unmounting LV (SV) (backup server) (1) Unmounting LV (SV) Unmount the logical volume used as a file system. umount /svfs1 (2) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the LV (SV) volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the LV (SV) disk group and make it offline. vxdg deport dg01 vxdisk offline sdb Step 10. Releasing a link between LV and SV (backup server) After unmounting, release a link between LV and SV. ismsc_unlink -lv lv001 -lvflg ld When you release a link before the daemon (vxconfigbackupd) processing, which is automatically performed after deport, in an environment where VxVM V4.0 or later is being used, the path may not be recognized from VxVM in rare cases. Therefore, it is recommended to wait (*) the daemon processing before link releasing. * Sleep processing for about two seconds. 26

33 Chapter 2 Operation and Maintenance Step 11. Canceling SV guard (backup server) Cancel SV guard classification set in Step 4. ismsc_svguard -bv bv001 -bvflg ld -sv.-1 -svflg relgen -mode cancel When you restart the backup server in the state just after performing Step 11 Canceling SV guard (backup server) while VxVM is being used, you need to follow the operations described in 3.4 Restarting Server Connecting to LV (SV) and return the backup server into normal operation. 27

34 Chapter 2 Operation and Maintenance Examplle off Resttoriing Busiiness Vollume Datta This section describes procedures of restoring business volume (BV) data Datta Resttorrattiion wiitthoutt Usiing Snapshott Functtiion When restoring data via network or restoring data on the business volume (BV) directly from backup data on the tape, execute data restoration following the procedure specific to the backup software. However, when a snapshot for BV to be restored has been created, be sure to delete the snapshot before restoration. LAN Application Server Backup Server Tape Device Backup Software Restore data on business volume (BV) via network. Restore business volume (BV) data directly using backup data on tape. BV SV LV Business Volume Snapshot Figure 2-2 Example of Data Restoration without Snapshot Function 28

35 Chapter 2 Operation and Maintenance Datta Resttorrattiion Usiing Snapshott Functtiion ((Logiicall Faulltt)) When a logical fault occurs due to an operation error by the user or AP abort, it is possible to recover BV by restoring the created snapshot to BV. In this section, assuming that a logical error occurs in the BV data file, the steps to recover data using a snapshot is described. Determine the snapshot to be restored by referencing the information such as the creation time displayed by the snapshot display function. For details on execution conditions of restoration, refer to the Snapshot User s Manual (Function Guide). In addition, it is assumed that the following information is given to each volume. BV: Logical disk name (bv001) SV: Logical disk name (sv001_01) LV: Logical disk name (lv001) LAN Application Server Backup Server Tape Device Backup Software Restore data on business volume (BV) directly using SV of any generation. BV SV LV Business Volume Snapshot Figure 2-3 Example of Data Restoration with Snapshot Function 29

36 Chapter 2 Operation and Maintenance Work flow of business volume data recovery (logic fault) example <<Application server>> <<Backup server>> Step 1. Terminating applications (1) Terminating applications (2) Unmounting BV (3) Deactivating the volume group Step 2. Restoration Step 3. Restarting applications (1) Activating the volume group (2) Mounting BV (3) Restarting applications Step 4. Waiting for restoration completion Step 1. Terminating applications (application server) Terminate or halt the operations and applications accessing the volume to be restored. The procedure is shown below. (1) Terminating applications Terminate the operations and applications that use BV. (2) Unmounting BV Unmount the logical volume used as a file system. umount /bvfs1 (3) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the BV volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the BV disk group. vxdg deport dg01 Step 2. Restoration (application server) Execute Restore on the BV volume. The following is an example for restoring BV from the snapshot of the latest generation. ismsc_restore -bv bv001 -bvflg ld -sv.-1 -svflg relgen -nowait 30

37 Chapter 2 Operation and Maintenance Step 3. Restarting applications (application server) Restart BV as the business volume. (1) Activating the volume group or importing the disk group If you use LVM, activate the BV volume group. vgchange -a y /dev/vg01 If you use VxVM, import the BV disk group. vxdg import dg01 vxvol -g dg01 startall (2) Mounting BV Mount BV (logical volume). If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /bvfs1 If you use VxVM, mount the VxVM logical volume. In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /bvfs1 (3) Restarting applications Restart the terminated operations (such as applications). Step 4. Waiting for restoration completion (application server) Wait for the restoration to complete. ismsc_wait -cond active -bv bv001 -bvflg ld -sv.-1 -svflg relgen 31

38 Chapter 2 Operation and Maintenance Datta Resttorrattiion Usiing Snapshott Functtiion ((Physiicall Faulltt)) When the BV data file or BV volume cannot be accessed due to a physical fault, BV can be recovered from a tape or another backup device. In this section, assuming that a physical fault occurs in the BV data file, the steps to recover BV from a backup medium are described. In addition, it is also assumed that a snapshot for the BV to be recovered has been created at the necessary point of time and backed up to a backup medium at that time. It is assumed that the following information is given to each volume. BV: Logical disk name (bv001) SV: Logical disk name (sv001_01) LV: Logical disk name (lv001) LAN Application Server Backup Server Tape Device Backup Software Link LV to BV and restore BV directly using backup medium. BV LV Business Volume SV Snapshot Figure 2-4 Data Restoration Procedure with Snapshot Function (Physical Fault) 32

39 Chapter 2 Operation and Maintenance Work flow of restoring data of the business volume (physical fault) example <<Application server>> <<Backup server>> Step 1. Terminating applications (1) Terminating applications (2) Unmounting BV (3) Deactivating the volume group Step 2. Repairing BV Step 3. Setting a link between LV and BV Step 4. Mounting LV (BV) Step 5. Restoring data from a backup medium to BV Step 6. Unmounting LV (BV) Step 7. Releasing a link between LV and BV Step 8. Restarting applications (1) Activating the volume group (2) Mounting BV (3) Restarting applications 33

40 Chapter 2 Operation and Maintenance Step 1. Terminating applications (application server) Terminate or halt the operations and applications that are accessing the volume where a fault has occurred. The procedure is shown below. (1) Terminating applications Terminate the operations and applications that use BV. (2) Unmounting BV Unmount the logical volume used as a file system. umount /bvfs1 (3) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the BV volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the BV disk group. vxdg deport dg01 Step 2. Repairing BV (application server) After rebinding and restoring BV from a hardware fault, recreate a logical volume and file system. After recreation, be sure to unmount BV and deactivate the volume group before executing Restore. (1) Unmounting BV Unmount the logical volume used as a file system. umount /bvfs1 (2) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the BV volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the BV disk group and make it offline. vxdg deport dg01 vxdisk offline sda 34

41 Chapter 2 Operation and Maintenance Step 3. Setting a link between LV and BV (backup server) To access BV from a backup server, link LV to BV. ismsc_link -lv lv001 -lvflg ld -bv bv001 -bvflg ld About setting a link to BV Setting a link to BV enables access to BV from a backup server, however, an access from an application server to BV is disabled. To set a link to BV, be sure to terminate operation and unmount BV from an application server. Step 4. Mounting LV (BV) (backup server) (1) Activating the volume group or importing the disk group If you use LVM, activate the LV (BV) volume group. vgscan vgchange -a y /dev/vg01 If you use VxVM, import the LV (BV) disk group after setting the disks online. vxdisk online sdb vxdg -C import dg01 vxvol -g dg01 startall (2) Mounting LV (BV) Mount LV (BV). If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /svfs1 If you use VxVM, mount the VxVM logical volume. In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /svfs1 Step 5. Restoring data from a backup medium to BV (backup server) Restore data saved in a backup medium to BV directly via LV using backup software. Step 6. Unmounting LV (BV) (backup server) (1) Unmounting LV (BV) Unmount the logical volume used as a file system. umount /svfs1 35

42 Chapter 2 Operation and Maintenance (2) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the LV (BV) volume group and delete the volume group information. vgchange -a n /dev/vg01 If you use VxVM, deport the LV (BV) disk group and make it offline. vxdg deport dg01 vxdisk offline sdb Step 7. Releasing a link between LV and BV (backup server) After Restore is completed, release a link between LV and BV. ismsc_unlink -lv lv001 -lvflg ld Step 8. Restarting applications (application server) Restart BV as the business volume. (1) Activating the volume group or importing the disk group If you use LVM, activate the BV volume group. vgscan vgchange -a y /dev/vg01 If you use VxVM, import the disk group after setting the BV disks online. vxdisk online sda vxdg -C import dg01 vxvol -g dg01 startall (2) Mounting BV Mount BV (logical volume). If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /bvfs1 If you use VxVM, mount the VxVM logical volume. In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /bvfs1 (3) Restarting applications Restart the terminated operations (such as applications). 36

43 Chapter 2 Operation and Maintenance Examplle off Secondary Use off Snapshotts This section describes how to build the same environment as that used for actual operations, using snapshots. (1) Overview The snapshot of the volume (BV) used for operations and updated daily is created regularly (for example, once a day). The snapshot where data for the necessary point of time is saved is accessed from a test operation via LV. Figure 2-5 shows an example of a system configuration. It is assumed that LV for access from SV (seven generations) and a backup server has been constructed for the volume, and operation has been started. It is also assumed that the following information is given to each volume. BV: Logical disk name (bv001) SV: Logical disk name (sv001_01 to sv001_07) LV: Logical disk name (lv001) Continue actual operation using BV. Set a link from LV to any snapshot and operate a test operation. Application Server Test Server Create snapshot regularly in accordance with operation policy. BV SV LV Business Volume Snapshot SV#2 SV#7 Figure 2-5 Secondary Use of Snapshots 37

44 Chapter 2 Operation and Maintenance Work flow of secondary use of snapshots example <<Application server>> <<Test server>> Step 1-1. Terminating applications Step 2-1. Setting a link between LV and SV (1) Terminating applications (2) Unmounting BV (3) Deactivating the volume group Step 2-2. Mounting LV (SV) (1) Activating the volume group (2) Mounting LV (SV) Step 1-2. Creating a snapshot Step 1-3. Restarting applications (1) Activating the volume group (2) Mounting BV (3) Restarting applications Step 2-3. Accessing a snapshot Step 2-4. Unmounting LV (SV) (1) Unmounting LV (SV) (2) Deactivating the volume group Step 2-5. Releasing a link between LV and SV 38

45 Chapter 2 Operation and Maintenance (2) Operation Procedure (application server) An application server creates a BV snapshot regularly. Step 1-1. Terminating applications (application server) You have to create a perfect static point of BV data before creating a snapshot. This is for completely writing all the data remaining in the cache to the disk. This task also intends to prevent I/O processing to/from the logical volume (file system) in order to maintain the data integrity between BV and snapshot. The procedure is shown below. (1) Terminating applications Terminate the operations and applications that use BV. (2) Unmounting BV Unmount the logical volume used as a file system. umount /bvfs1 (3) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the BV volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the BV disk group. vxdg deport dg01 Step 1-2. Creating a snapshot (application server) Create a snapshot on SV and enable operations to be restarted. When you create a snapshot, check whether the snapshot of the oldest generation is not used from a test operation. ismsc_create -bv bv001 -bvflg ld -cyclic Step 1-3. Restarting applications (application server) Restart BV as the business volume. (1) Activating the volume group or importing the disk group If you use LVM, activate the BV volume group. vgchange -a y /dev/vg01 If you use VxVM, import the BV disk group. vxdg import dg01 vxvol -g dg01 startall 39

46 Chapter 2 Operation and Maintenance (2) Mounting BV Mount BV (logical volume). If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /bvfs1 If you use VxVM, mount the VxVM logical volume. In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /bvfs1 (3) Restarting applications Restart the terminated operations (such as applications). (3) Operation Procedure (test server) Step 2-1. Setting a link between LV and SV (test server) To access a snapshot, set a link between LV and SV. Setting a link enables access to SV depending on the access restriction specified at setting a link. ismsc_link -lv lv001 -lvflg ld -sv bv svflg ld.relgen * Hereafter, the snapshot linked to LV is referred to as LV (SV). Step 2-2. Mounting LV (SV) (test server) (1) Activating the volume group or importing the disk group If you use LVM, activate the LV (SV) volume group. vgscan vgchange -a y /dev/vg01 If you use VxVM, import the LV (SV) disk group after setting the disks online. vxdisk online sdb vxdg -C import dg01 vxvol -g dg01 startall (2) Mounting LV (SV) Mount LV (SV) (logical volume). If you use LVM, mount the LVM logical volume. In this example, ext3 is used as a file system. mount -t ext3 /dev/vg01/lvol /svfs1 If you use VxVM, mount the VxVM logical volume. 40

47 Chapter 2 Operation and Maintenance In this example, VxFS is used as a file system. mount -t vxfs /dev/vx/dsk/dg01/lvol /svfs1 Step 2-3. Accessing a snapshot (test server) Access a snapshot from a test operation to execute a test. After the test is completed and the target volume is not accessed anymore, proceed to the next step. Step 2-4. Unmounting LV (SV) (test server) (1) Unmounting LV (SV) Unmount the logical volume used as a file system. umount /svfs1 (2) Deactivating the volume group or deporting the disk group If you use LVM, deactivate the LV (SV) volume group. vgchange -a n /dev/vg01 If you use VxVM, deport the LV (SV) disk group and make it offline. vxdg deport dg01 vxdisk offline sdb Step 2-5. Releasing a link between LV and SV (test server) After unmounting, release a link between LV and SV. ismsc_unlink -lv lv001 -lvflg ld When you release a link before the daemon (vxconfigbackupd) processing, which is automatically performed after deport, in an environment where VxVM V4.0 or later is being used, the path may not be recognized from VxVM in rare cases. Therefore, it is recommended to wait (*) the daemon processing before link releasing. * Sleep processing for about two seconds. 41

48 Chapter 2 Operation and Maintenance 2..3 Measures for Errors This section describes how to take measures for errors that occur during snapshot operation. The following faults are described in this section. (1) Snapshot fault (2) ism Server or client fault (3) SnapControl abnormal end (4) Invalid product How to collect information necessary to analyze unidentified faults is also described Snapshott Faulltt This section describes the causes of inability to access a snapshot and the measures. (1) Insufficient Snapshot Reserve Area (SRA) Effect when insufficient SRA capacity occurs If data is written to a business volume (BV) where a snapshot is created with insufficient SRA area, the created snapshot is deleted automatically as extended operation of write and the status becomes snapshot inactive (snap/inactive). When a backup server accesses a snapshot, the link setting between LV and SV is released and the snapshot is deleted. Therefore, I/O is terminated abnormally because the server operates in the same way as a disk failure. In this case, restart the backup server as the file system may be invalid. If you use LVM, execute operations according to the following procedures. Separating the volume group (Refer to Operations for LVM Volume Group.) Restarting the server If you use VxVM, execute operations according to the following procedures. Separating the disk group (Refer to Operations for VxVM Disk Group.) Restarting the server Enabling disk devices to be used online (When they are reused, execute this procedure after setting a link.) Check and measures You can check SRA capacity from the main window of the ism client. When the SRA capacity is insufficient, take one of the following measures to obtain enough capacity. 42

49 Chapter 2 Operation and Maintenance SRA expansion Obtain differential management area of the snapshot by expanding the SRA capacity. Expand the SRA capacity on the configuration setting screen of the ism client. For the detailed procedure, refer to the Snapshot User s Manual (Function Guide). Deleting an unnecessary snapshot Release the differential management area of the occupied snapshot by deleting an unnecessary snapshot. Since a snapshot of the oldest generation occupies a great amount of space generally, you can have great effect if you delete the oldest one. You can delete a snapshot on the Snapshot management screen of the ism client. For the detailed procedure, refer to the Snapshot User s Manual (Function Guide). (2) SRA Fault Effect when an SRA fault occurs When SRA becomes unavailable due to a fault, none of the snapshots that share the SRA can be accessed. Check and measures It may be caused by a physical fault of SDV constituting SRA or a physical fault of the pool where SRA is stored. On the main window of the ism client, you can check whether a fault occurs. After a fault recovery, create SRA and the snapshot again. (3) BV fault Effect when a BV fault occurs When a physical fault occurs in BV, none of snapshots of all generations set in BV can be accessed. Check and measures You can check whether a physical fault occurs in BV on the main window of the ism client. When a BV physical fault occurs, recover from the fault executing the following steps. Deleting LV Delete LV on the configuration setting screen of the ism client. Deleting generations Delete snapshots of all generations on the configuration setting screen of the ism client. Recovery from a fault Eliminate the cause of a fault and rebind BV. Recreating generation Recreate the snapshot generation on the configuration setting screen of the ism client. Recreating LV Recreate LV on the configuration setting screen of the ism client. For the logical disk number created as LV, you need to assign the same number as that of the logical disk before deletion. 43

50 Chapter 2 Operation and Maintenance iism Server or Clliientt Faulltt For faults when the ism server and the ism client are used, refer to the User s Manual (UNIX) Abnormall End off SnapConttroll SnapControl outputs error contents or messages to the standard output, standard error output, system log, command trace, or operation trace when an error has occurred. The standard output, standard error output, system log, or command trace records the messages described in the Messages Handbook. Take necessary actions depending on the message. The command trace is output in the etc folder under the folder where SnapControl has been installed (/opt/ismrpl/etc/) as a text file beginning with ism_log. Check the contents using a text editor. The internal information necessary for analyzing faults is recorded in operation trace IInvalliid Productt If the product for snapshot has not been purchased or if it does not match the total physical capacity of the disk array, the snapshot does not function properly. If the products are not purchased properly, the icon on the Snapshot management screen (tree view) changes to indicate missing products or products not purchased. For purchased products, check disk array Properties in the State Monitoring screen Collllecttiing IInfformattiion off Error off Unknown Cause When an error whose cause is unknown has occurred and you want to request the provider to investigate the error, you must collect information required for error analysis. (1) Fault by ism operation When a fault occurs by ism operation, refer to the User s Manual (UNIX) and collect information. (2) For SnapControl error Follow the steps below to execute the command and collect fault information at a time. A disk for storing fault information must have at least about 4 MB of unused space. The total size of fault information files differs depending on the system status, and it may exceed 4 MB. It is advisable to allocate an unused space of enough size. 44

51 Chapter 2 Operation and Maintenance (1) Log in as root. (2) Execute the ismvolgather command. # ismvolgather [Directory name] * Be sure to specify the directory name with the absolute path name. (3) The ismvolgather directory is created under the /opt/ismvol/ directory if you do not specify any directory name. If you specify a directory, the ismvolgather directory is created under the specified directory. Check that the ismvolgather.tar.z file or ismvolgather.tar.gz file is created under the directory and obtain the file. 45

52 Chapter 2 Operation and Maintenance 2..4 Operatiions when the Confiiguratiion iis Changed It is necessary to recreate the volume list to reflect the new configuration information to the volume list when you change the disk array or server (OS) configuration Condiittiions Requiiriing Vollume Liistt Updatte Be sure to recreate the volume list after changing the following configurations: Change of disk array configuration Change of disk array name Change of logical disk name Change of logical disk OS type Adding of logical disk, and change and deleting of configuration Adding and deleting of snapshot generation and link-volume Change of Access Control setting Adding and deleting of disk array connected by RemoteDataReplication If the disk array configures RemoteDataReplication and the above configuration changes are done in the remote-side disk array, update the volume list as well. Change of server configuration Adding, deleting and change of control volume definition (only when the control volume is used) Change of connection configuration (path) between the disk array and server 46

53 Chapter 2 Operation and Maintenance Updattiing Vollume Liistt To update a volume list, execute the ismvollist command with the -r option specified. Update a volume list with the appropriate user privilege. When updating a volume list, note the following points so that the information to be registered in the volume list including the logical disk and volume information already registered is complete. Update a volume list in the following states. - The path between the disk array and the server is normally connected. - The logical disk in the disk array is recognized as a server (OS) disk device. - The volume in the disk is recognized by the server (OS). Especially in the server connected to the LV, the LV may not be recognized by the server (OS) when the server restarts while the LV is in the Not Ready (unavailable for read or write) state. In such a case, it is required to have the OS recognize the LV again. For how to restart the server connected to the LV and restore operations to have the OS recognize LV again, refer to 3.4 Restarting Server Connecting to LV (SV). If the ism server is running on the same server, it is required to exit ism before updating volume list. When you add, delete or change the control volume definition in the disk array with which the control volume attribute cannot be identified, execute the following operation before updating a volume list. - Define the logical disk to be used as the control volume in advance in the control volume definition file. 47

54 Chapter 2 Operation and Maintenance To successfully register volume information in the volume list, update a volume list in the following states. - Pairs are separated when the RV is connected to the server. - The link-volume (LV) and snapshot-volume (SV) are linked when the LV in the snapshot function is connected to the server. The base-volume (BV) and LV are not linked when the BV is connected to the server. - Protected data is readable when the logical disk for which the data retention function is applied is connected to the server. - The volume is in the In use state and accessible when the logical disk for which the power saving function is applied is connected to the server. - The link path between disk arrays is normal when the RemoteDataReplication is configured for the disk array. After updating a volume list, display the information registered in the volume list to check that the items to be used such as logical disks and special file names are all registered correctly. If the script or others used for operation describes the logical disks, special file names, and other information to be operated, reflect the updated information in the volume list to that file. Note that the snapshot operation command execution may abnormally end in the future operation if the information in the volume list contains an error or if the volume list information is inconsistent with the script or others used for operation. 48

55 Chapter 3 Notes Chapter 3 Notes This chapter describes some notes regarding management and operations of snapshot Snapshot Access Restriictiion Sellectiion When you create, delete, or restore a snapshot, access restriction to BV is not changed but Read/Write (RW) remains effective. If, however, a link from LV to BV is set, access can be made only via LV during link setting. To use SV, you need to set a link from LV. At this time, you can select Read/Write (RW) or Read Only (RO), but usually use Read/Write (RW). If Read Only (RO) is set, operations vary depending on which operating system and file system you use. Do not use Read Only (RO) unless you are familiar with the operating system and file system operations. You can set a link to SV only while a snapshot is activated (snap/active). Table 3-1 lists access restrictions available at a link setting. Access Restriction Table 3-1 Access Restriction at Link Setting Description Status snap/active Read/Write (RW) Read/Write enabled Read Only (RO) Read only enabled * Not Ready (NR) Read/Write disabled * Not Available (NA) Not recognized by the operating system or the LU (Logical Unit) invalid * : Available *: Available with administrative restrictions snap/active: Activating snapshot RW: Read/Write, RO: Read Only, NR: Not Ready, NA: Not Available Note the following depending on the setting value of the access restriction at a link setting. When mounting the LV (SV) file system of which access restriction is RO (Read Only), specify the Read Only setting. If you use the VxVM disk group, set access restriction of the target volume as RW (Read/Write). If there is a volume with RO (Read Only), the disk group cannot be imported. 49

56 Chapter 3 Notes If an access is made to a volume in Not Ready state or Read Only state, such as an unlink LV or access-restricted LV, a message indicating an SCSI error (refer to the <Message Example> below) may be recorded in syslog. If you execute a command, such as fsck, that tries to access all volumes in a server, a message similar to the example below may be recorded for every volume in the server in Not Ready state or Read Only state. <Message Example> Dec 10 14:48:14 sv001 kernel: SCSI error : < > return code = 0x Dec 10 14:48:14 sv001 kernel: Info fld=0x0, Current sde: sense key Data Protect Dec 10 14:48:14 sv001 kernel: ASC=f4 ASCQ= a Dec 10 14:48:14 sv001 kernel: end_request: I/O error, dev sde, sector 0 In an environment that has PathManager installed, if such a message is recorded, the PathManager path to the volume may be broken, preventing the volume from being accessed. Set the link of the LV in Read/Write mode to make the volume Read/Write-enabled, and then recover the broken path using the recoverpath command of PathManager. If the path to a volume a volume in Read Only state is broken, recovery is automatically performed by path monitoring of PathManager after a fixed time period (monitoring interval). For details on PathManager, refer to the PathManager User s Manual (Linux). In an environment that does not have PathManager installed, there is no operational problem even if a message similar to the above example is recorded Access Riight Settiings on Fiilles iin Vollumes Access right and owner information (such as a user ID and group ID) on directories and files in volumes used in BV or SV is reflected on SV (or BV) after snapshot creation (or restoration), and existing access right settings and owner information are overwritten. If the overwritten access right settings are different from existing settings, the access to directories or files used before may be disabled. Therefore, access right on directories or files and owner information (such as a user ID and group ID) must be specified the same on BV and SV servers. 50

57 Chapter 3 Notes 3..3 Vollume Operatiions of LVM and VxVM Usiing LVM and VxVM (1) Volumes to Be Managed Take extra care when using LVM or VxVM because using the snapshot and BV within the same server causes an operational failure. If you use LVM or VxVM, BV and SV must operate in different servers. Application Server A Unavailable BV Business Volume SV LV Snapshot Figure 3-1 Snapshot Use Restrictions within the Same System When the volume group is used, snapshot operation is performed per logical disk. Therefore, it is advisable to make up a volume group with a single logical disk. When the volume group consists of multiple logical disks, these logical disks may not maintain the data integrity in the volume group if a logical disk operation partly fails due to a faulty operation or other causes. Therefore, extra care is required for such an operation. Especially during hot backup operation (that is, the volume group is neither unmounted nor deactivated) in the environment where the volume group consists of multiple logical disks, carefully make an arrangement so that the logical volume built in the volume group does not extend across multiple logical disks. 51

58 Chapter 3 Notes (2) Volumes Not to Be Managed If you perform snapshot operation using the volume that is not managed and that has been already operated as BV, SV (LV) should not be managed. If either of them belongs to the volume group, snapshot creation and restoring may destroy the volume management information. To prevent such an accident, make sure that both BV and SV (LV) are not to be managed before starting snapshot operations when you use logical disks not to be managed for operation Operattiions ffor LVM Vollume Group To create the business volume (BV) snapshot for backup and other operations, you have to stop data update to the business volume and completely write all data in the OS cache to the business volume in order to obtain a data static point. Thus, before creating a snapshot, temporarily separate the LVM volume group from your applications by unmounting the file system and deactivating the volume group (however, this task is not required when the system has the function to back up data without stopping applications using a database or other optional products). After snapshot creation is completed, you can resume data update to the business volume. To apply the LVM volume group to your applications, activate the volume group and mount the file system. You have to perform the following operations to apply the LVM volume group to applications. If you do not use any file systems, you do not have to mount or unmount a file system. The following procedure is for BV in a non-cluster system before snapshot creation. - Activating the volume group Example of activating volume group vg01 vgchange -a y /dev/vg01 - Mounting the file system Example of mounting the ext3 file system in volume group vg01 mount -t ext3 /dev/vg01/lvol /mnt1 You have to perform the following operations to separate the LVM volume group from applications. 52

59 Chapter 3 Notes - Unmounting the file system Example of unmounting the file system from /mnt1 umount /mnt1 - Deactivating the volume group Example of deactivating volume group vg01 vgchange -a n /dev/vg01 If a volume group is operated in the state that a server includes a volume in the Not Ready state such as an unlink LV, a message indicating a SCSI error (See the <Message Output Example> below.) is recorded in syslog. There is, however, no problem in operation. <Message Output Example> Dec 10 14:48:14 sv001 kernel: SCSI error : < > return code = 0x Dec 10 14:48:14 sv001 kernel: Info fld=0x0, Current sde: sense key Data Protect Dec 10 14:48:14 sv001 kernel: ASC=f4 ASCQ= a Dec 10 14:48:14 sv001 kernel: end_request: I/O error, dev sde, sector Operattiions ffor VxVM Diisk Group To create the business volume (BV) snapshot for backup and other operations, you have to stop data update to the business volume and completely write all data in the OS cache to the business volume in order to obtain a data static point. Thus, before creating a snapshot, temporarily separate the VxVM disk group from your applications by unmounting the file system and deporting the disk group (however, this task is not required when the system has the function to back up data without stopping applications using a database or other optional products). After snapshot creation is completed, you can resume data update to the business volume. To apply the VxVM disk group to your applications, import and activate the disk group and mount the file system. To use a snapshot (SV), you also need to import and activate the disk group and mount a file system. You have to perform the following operations to apply the VxVM disk group to applications. If you do not use any file systems, you do not have to mount or unmount a file system. 53

60 Chapter 3 Notes - Importing the disk group Example of importing and activating disk group dg01 vxdg import dg01 vxvol -g dg01 startall - Mounting the file system Example of mounting the VxFS file system in disk group dg01 mount -t vxfs /dev/vx/dsk/dg01/vol1 /bvfs1 You have to perform the following operations to use the VxVM disk group on a backup server. If you do not use any file systems, you do not have to mount or unmount a file system. - Importing the disk group To use a snapshot from a backup server, use the -C option of the vxdg command after setting the disks online. vxdisk online sdb vxdg -C import dg01 vxvol -g dg01 startall - Mounting the file system Example of mounting the VxFS file system in disk group dg01 mount -t vxfs /dev/vx/dsk/dg01/vol1 /bvfs1 You have to perform the following operations to separate the VxVM disk group from applications. - Unmounting the file system Example of unmounting the file system from /bvfs1 umount /bvfs1 - Deporting the disk group Example of deporting disk group dg01 vxdg deport dg01 Example of deporting disk group dg01 from a backup server vxdg deport dg01 vxdisk offline sdb When restarting a backup server on which the LV is in Not Ready state by executing unlink operation, VxVM may not recognize the RV disk. When such an event occurs, be sure to make VxVM recognize the RV by taking the following steps. 54

61 Chapter 3 Notes Step 1. Releasing the LV from Not Ready state (application server) Set a link to LV, which is unlinked, to release the RV from Not Ready state. Link operation can be executed from the ism snapshot management as well. Step 2. Restarting the server (backup server) Restart a backup server to which LV disk is connected and make OS and VxVM recognize the LV disk and partition information. After restarting the server, make the LV disk offline. vxdisk offline sdb Step 3. Releasing a link of LV (backup server) Release a link of LV to start backup operation. ismsc_unlink -lv lv001 -lvflg ld If an arbitrary disk group is imported in the state that a backup server includes a volume in Not Ready state such as an unlink LV, a message indicating a SCSI error (See the <Message Output Example> below.) is recorded in syslog. There is, however, no problem in operation. <Message Output Example> Mar 18 00:41:18 sv001 kernel: SCSI disk error : host 2 channel 0 id 1 lun 6 return code = Mar 18 00:41:18 sv001 kernel: Info fld=0x0, Current sd08:80: sense key Data Protect Mar 18 00:41:18 sv001 kernel: SCSI disk error : host 2 channel 0 id 1 lun 6 return code = Mar 18 00:41:18 sv001 kernel: Info fld=0x0, Current sd08:80: sense key Data Protect 55

62 Chapter 3 Notes Usiing tthe Speciiall Fiille ffor PatthManager To use the PathManager special file (/dev/ddx, X is a lower-case alphabet) in LVM, the following products are required. ControlCommand Ver5.1 or later PathManager function version or later *Refer to the PathManager manual for more support information of LVM. Snapshot operation to the volume group where the PathManager special file was created as a physical volume is the same as the operation to the volume group created using the kernel special file (/dev/sdx, X is a lower-case alphabet). For details, refer to Using LVM and VxVM and Operations for LVM Volume Group. To use the PathManager special file in LVM, refer to the PathManager manual and LVM manual. 56

63 Chapter 3 Notes Changiing Conffiigurattiion Usiing Access Conttroll The following phenomena may occur during snapshot operation if you have not perform the operation described in the VxVM manual (regenerating the disk access name) after changing the LD configuration by setting the Access Control (*) in VERITAS Volume Manager 4.1 or later. The operation may be performed for an LD other than that in the disk group when the disk group (DG) is specified. The system may abnormally terminate due to mount check error during restore processing. Regenerating the VxVM disk access name in addition to the conventional operation procedures after changing the LD configuration (*). (*) LUN number reallocation or change that causes the LD special file name to change Step 1. Operations to the volume in the Not Ready state and rebooting the OS (conventional step) If the volume in the Not Ready state exists on the server, change it to the status where the read/write operation is possible. Reboot the OS to make the changed configuration recognized. Step 2. Regenerating the VxVM disk access name Regenerate the VxVM disk access name to correspond with the special file name. Perform the following operations by the root account. (1) Delete the following file, which retains the disk access name. rm /etc/vx/disk.info (2) Restart the VxVM configuration daemon and regenerate the disk access name. vxconfigd -k Do not execute any VxVM command while restarting the configuration daemon. Step 3. Re-creating the volume list (conventional step) Re-create the volume list. ismvollist -r The procedure for regenerating the VxVM disk access name is described in Regenerating the Persistent Device Name Database in the VERITAS Volume Manager 4.1 Administrator s Guide. Refer to the VERITAS documents as well when using the VERITAS Cluster Server because it is necessary to operate the service group. 57

64 Chapter 3 Notes 3..4 Restartiing Server Connectiing to LV (SV) When restarting a server to which LV (SV) is connected, you may not use an LV volume from OS. This is because OS cannot recognize the LV (SV) partition information when the LV is in Not Ready state by executing Unlink operation on restarting the server. When such an event occurs, it is necessary to make OS recognize the LV partition information by taking the following steps. Step 1. Releasing the LV from the Not Ready state (backup server) Set a link to LV, which is unlinked, to release it from Not Ready state. Link operation can be executed from the ism snapshot management as well. Step 2. Restarting the server (backup server) Restart the server to which LV is connected to make OS recognize the LV partition information. If LV is used as a VxVM disk group, make the LV disk offline after restarting the server. vxdisk offline sdb Step 3. Releasing a link of LV (backup server) Release a link of LV to start backup operation. ismsc_unlink -lv lv001 -lvflg ld 3..5 Controll Vollume A control volume is used when a server issues control I/O to the relevant disk array. Register in advance one logical disk for each disk array as the volume for issuing I/O to that disk array in the volume List. Prepare one control volume for each server. It is not advisable to use the same logical disk as the control volume from different servers. To register a control volume, use a normal volume that is not used for data replication and snapshot. Keep the volume assigned as a control volume as a dedicated volume, and do not assign business data to the volume. For a logical disk used as a control volume, the RAID format and capacity are not limited. You can build a small-capacity logical disk dedicated for a control volume. For details on how to build a control volume, refer to the Configuration Setting Tool User s Manual (GUI). For details on how to define a control volume, refer to 1.5 Control Volume Setting. 58

65 Chapter 3 Notes 3..6 Management and Operatiions of Snapshot (1) You can execute snapshot operations such as snapshot creation and restoration by using the ism s snapshot control function. However, the operations from ism are asynchronous with business operation, and trouble may occur. To execute these snapshot operations, therefore, use the SnapControl in principle that operates on the application server. (2) To ensure data consistency, keep the following in mind: To create a snapshot, keep a static point by mounting BV and the like. To create a snapshot, release a link of the target SV. Before executing Restore, unmount the BV and SV (LV). Do not create snapshot until BV is completely updated and the cache data in the OS file system is reflected to the disk. Otherwise, ill-defined data may be reflected to the snapshot as is. (3) Snapshot creation and restoration are executed in units of disks, not in units of logical volumes managed by LVM or VxVM. Be careful in setting and operating LVM or VxVM. To prevent operation errors and trouble, the volume management settings on the BV and SV sides must be the same for all the servers. (4) To use VxVM, use BV and SV (LV) on different servers. You cannot mount BV and SV (LV) on the same server to use. This is because that the volume management information on BV and SV becomes the same, so you cannot mount BV and SV concurrently. (5) If an I/O error is detected during disk array access and an alternative path is used, the special file information displayed at command execution will be displayed as follows. The specified special file appears when the volume is executed with sfn specified. The special files of individual groups (the information on the primary path) appear when the volume is executed with vg or dg specified. The special file with an alternative path appears when the volume is executed with ld specified. (6) Mirroring a redundant volume supplied by LVM and VxVM is not supported. (7) In the cluster environment, install SnapControl in all servers of the operating system and standby system. The servers cannot share the environment settings. Create the volume list and make the environment setting same for all servers including the control volume definition and software operation setting. (8) To register a logical disk to use in the volume list, you should have created a special file in /dev/sd# format for that logical disk. Create all special files for the logical disks to use with the /dev/makedev or mknod command before creating or updating the volume list. (9) To specify a special file name in the command option, use the format of /dev/sd#. The displayed special file name is also in this format. (10) Set sequential numbers beginning with 0 to the LUNs assigned to logical disks. The system only recognizes the logical disks associated to LUNs with sequential numbers beginning with 0. If you set a nonsequential number to a LUN, the corresponding and subsequent logical disks are not recognized. (11) You have to restart the system to add or delete disk arrays. 59

66 Chapter 3 Notes (12) To use a partitioned volume on a backup server, you have to set a link on the backup server beforehand, and write partition information to the disk by a partition table operation tool (such as the fdisk command). If you use VxVM, since a volume is partitioned automatically when it is initialized as the VM disk, you also have to write partition information as in the case of you partitioning a volume Liinkiing wiith Replliicatiion Functiion (1) To create a snapshot using the RV of DDR or RDR as the BV, the license of DynamicSnapVolume Version3 is required. Concerning the disk array pair connected to use RDR, when one disk array is monitored by the ism and other is not, you must pay attention. In this configuration, when the license of DynamicSnapVolume in a disk array outside ism management is upgraded to Version3, you have to reboot the ism. (2) To create a snapshot using the RV of DDR as the BV, the RV must be separated (separated). When you perform Separate (immediate) of the replication function, the RV becomes available (available for read or write), however, a snapshot cannot be created. Wait for separated (separated) Recommended Confiiguratiion for SATA Diisk Modell An SATA disk has the recommended and not recommended configuration by its disk performance. [Recommended configuration] An RV of DDR/RDR is created on the SATA disk and then a snapshot is created with this as the BV. [Configuration not recommended] The business volume is created on the SATA disk and then a snapshot is created with this as the BV. 60

67 Index A abnormal end...44 Access Control...2 Access Control setting...10 access right settings on files in volumes...50 AccessControl...10 activating the volume group... 25, 31, 35, 36, 39, 40, 52 alternative path...59 E example of backup operation...22 example of secondary use of snapshots...37 G generation...8 B backup...26 backup software...35 basic pool...6 binding a link-volume...10 binding a logical disk (LD)...6 binding a snapshot-volume...10 binding the snapshot reserve area...9 BV fault...43 C change of disk array configuration...46 change of server configuration...46 collecting information of error of unknown cause...44 command trace...44 conditions requiring volume list update...46 configuration example of a logical disk...7 control volume... 6, 11, 58 control volume definition file...12 control volume registration...13 control volume setting...11 creating a generation...17 creating a snapshot... 24, 39 ctlvol.conf...12 H hardware configuration...2 I importing the disk group...54 individual ports...10 individual WWNs...10 insufficient snapshot reserve area...42 insufficient SRA capacity...42 invalid product...44 ism...3 ism server installation...4 ism server setting...4 ism server uninstallation...4 ism server update...4 ismsc_create...24 ismsc_link...25, 35 ismsc_restore...30 ismsc_svguard...24, 27 ismsc_unlink...26, 36 ismsc_wait...31 ismvolgather...45 ismvollist...47 ismvollist -ctl...13 D data replication function...11 data restoration (logical fault)...29 data restoration (physical fault)...32 deactivating the volume group... 26, 30, 36, 39, 41, 53 deleting an unnecessary snapshot...43 deporting the disk group... 39, 41, 54 disk array subsystem name setting...8 disk group...53 dynamic pool...6 DynamicSnapVolume...3, 6 L linking with replication function...60 logical disk...6 logical disk name setting...8 logical fault...21 LVM... 16, 51, 52 M management and operations of snapshot...59 mirroring a redundant volume...59 mkfs

68 mount... 25, 26, 31, 35, 36, 40, 41, 52, 54 mounting... 25, 31, 35, 36, 40 mounting the file system... 52, 54 N NA...49 Not Available...49 Not Ready...49 NR...49 number of generations...10 O operation trace...44 operations when the configuration is changed...46 OS type of a logical disk...8 P physical fault...21 pool...6 port name setting...8 product license unlocking...6 R Read Only...49 Read Only (RO)...49 Read/Write...49 releasing a link... 26, 36, 41 repairing BV...34 restoration... 30, 31 restore...35 RO...49 rst/exec...49 RW...49 S setting a link... 25, 35, 40 setting a link to BV...35 snap/active...49 SnapControl...3, 5 snapshot access restriction...49 snapshot management...4 snapshot management (GUI)...4 snapshot management (GUI) installation...4 snapshot management (GUI) uninstallation...4 snapshot reserve area...9 software configuration...3 software installation...4 SRA...6, 9 SRA expansion...43 SRA fault...43 standard error output...44 standard output...44 system log...44 U umount... 26, 39, 41, 53, 54 unmounting... 26, 39, 41 unmounting the file system...53, 54 updating volume list...47 V vgcfgbackup...17 vgchange...24, 25, 26, 30, 34, 36, 39, 40, 41, 52 vgscan... 25, 35, 36, 40 volume group...52, 56 volume list...46 volume list creation...14 vxdg...54 VxVM...18, 53 vxvol...54 W wait...31 SDV