PS Series Storage Arrays

Transcription

1 PS Series Storage Arrays iscsi Initiator and Operating System Considerations June 2010

2 Copyright 2010 Dell, Inc. All rights reserved. EqualLogic is a registered trademark of Dell, Inc. Dell is a trademark of Dell, Inc. All trademarks and registered trademarks mentioned herein are the property of their respective owners. Information in this document is subject to change without notice. Reproduction in any manner whatsoever without written permission is strictly forbidden. June 2010 Part Number: EN Rev. 1

3 Table of Contents Overview... 1 Microsoft iscsi Initiator... 1 Increase TimeOutValue Parameter to Avoid Disk I/O Timeouts... 1 Increase Transmit and Receive Resource Settings... 1 Microsoft iscsi Software Initiators for Clustered, Multi-Path I/O Environments... 1 Microsoft iscsi Software Initiators for Single System, No Multi-Path Environments... 2 QLogic iscsi Host Bus Adapters... 3 Other Issues... 3 Operating Systems... 4 Microsoft Windows... 4 Other Issues... 5 Linux... 5 Red Hat 3.0 or Higher Enterprise Server or Advanced Server and Bundled iscsi Driver... 5 Red Hat 5.1 and 5.2 Using IPv6 is not Supported... 5 Configuring Disk Timeout for Linux 2.6 Kernel SCSI Devices... 5 Solaris NetWare... 6 Related Documentation and Customer Support... 7 Contacting Dell... 7 PS Series Storage Arrays: iscsi Initiator and Operating System Considerations iii

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5 Overview This document describes configuration requirements, limitations, and other considerations related to iscsi initiators and the operating systems on which they are installed. If you are running any of the operating systems or iscsi initiators described in the following sections, make the suggested modifications before performing firmware updates in order to reduce the chance of I/O disruptions. You should also make sure that your applications can tolerate longer-than-normal I/O times. In all cases, you should first test the suggested modifications in a non-production environment. If you are not running any of the operating systems or iscsi initiators listed here, or if you are unsure of your applications ability to tolerate long I/O times, consider planning for downtime when updating firmware. This can involve shutting down the hosts accessing the group before beginning the update procedure. After the update completes, you can restart the hosts. Microsoft iscsi Initiator The following configuration updates must be made to the Microsoft iscsi initiator: Increase TimeOutValue Parameter to Avoid Disk I/O Timeouts Increase the value of the TimeOutValue parameter (HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/ Services/Disk/TimeOutValue) to at least 60 seconds (the default is 10 seconds). Make sure to set the type to DWORD and enter the decimal value (60). This will increase the timeout period for all disk I/Os for the disk class driver (in contrast to driver-specific Registry parameters that affect only your iscsi initiator). You must reboot the server for the change to take effect. WARNING: Use the Registry Editor carefully. Using the Registry Editor incorrectly may cause serious problems requiring you to reinstall your operating system. Dell and Microsoft cannot guarantee that you will be able to solve problems that result from using the Registry Editor incorrectly. Increase Transmit and Receive Resource Settings A PS Series group may deliver more network I/O than iscsi initiators can handle, resulting in dropped packets and retransmissions. However, some iscsi initiators let you increase the transmit and receive resource settings, which can help prevent this problem. For example, on a Windows system, you may be able to increase the initiator's network interface settings for receive and transmit descriptors. On a UNIX or Linux system, increase the transmit and receive resources for your network ports. Microsoft iscsi Software Initiators for Clustered, Multi-Path I/O Environments See the EqualLogic support website specified under Contacting Dell on page 7 for the latest recommended initiator versions. There are two recommended modifications: For clustered environments using multi-path I/O, set the LinkDownTime parameter to 35 seconds, and set the PS Series Storage Arrays: iscsi Initiator and Operating System Considerations 1

6 TimeOutValue parameter to 60 seconds. For any environment (clustered or not) using multi-path I/O, make the following changes: Add or modify the UseCustomPathRecoveryInterval key, and set its value to 1. For 64-bit Windows Server 2008 R2 clusters with high numbers of connections (approximately 700 or more), add or modify the PDORemovePeriod key, and set its value to 240. For other cluster configurations, set the PDORemovePeriod value to 120. Add or modify the PathRecoveryInterval key, and set its value to 60. WARNING: Use the Registry Editor carefully. Using the Registry Editor incorrectly may cause serious problems requiring you to reinstall your operating system. Dell and Microsoft cannot guarantee that you will be able to solve problems that result from using the Registry Editor incorrectly. Validate these parameter settings after installing the Host Integration Tools (if applicable). Some versions of the Host Integration Tools may modify these values. Table 1 summarizes the keys to change, and their recommended values. The first column lists the Registry Parameter, and the second lists the recommended value for it. Parameter Table 1: Registry Parameters for Clustered, Multi-Path I/O Environments HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\ {4D36E97B-E325-BFC BE10318}\0000\Parameters\LinkDownTime HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Disk\TimeOutValue HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\mpio\Parameters\ UseCustomPathRecoveryInterval 64-bit Windows Server 2008 R2 clusters with high numbers of connections: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\mpio\Parameters\PDO RemovePeriod All other cluster configurations: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\mpio\Parameters\PDO RemovePeriod HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\mpio\Parameters\ PathRecoveryInterval Microsoft iscsi Software Initiators for Single System, No Multi-Path Environments Value 35 (Decimal) 60 (Decimal) 1 (DWORD) 240 (Decimal) 120 (Decimal) 60 (Decimal) See the support website specified under Contacting Dell on page 7 for the latest recommended initiator versions. This modification applies only if: You are not using multi-path I/O You are not running a cluster environment Set the MaxRequestHoldTime parameter to 300 seconds (5 minutes). To find this parameter, navigate to: 2 PS Series Storage Arrays: iscsi Initiator and Operating System Considerations

7 HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E97B-E325 <HOSTid>} Under this key you will see at least one subkey named 0000, or 0001, or 0002, and so on. Expand each subkey until you find one that has a subkey called Parameters. Within that subkey is the MaxRequestHoldTime parameter. Although an array will not take five minutes to restart, you must increase the iscsi initiator timeout value to five minutes (300 seconds). This will increase the time that the operating system can tolerate a disruption in service due to an array restart by increasing the amount of time that an I/O will wait for completion. WARNING: Use the Registry Editor carefully. Using the Registry Editor incorrectly may cause serious problems that requiring you to reinstall your operating system. Dell and Microsoft cannot guarantee that you will be able to solve problems that result from using the Registry Editor incorrectly. QLogic iscsi Host Bus Adapters The following configuration changes must be made to the parameters of QLogic adapters: Set the default Keep-Alive TimeOut (KATO) to at least 120 seconds. Turn on ARP Redirect. For detailed information on this modification and information about booting, see the Solutions page on the customer support website specified under Contacting Dell on page 7. Also, for volumes with very low I/O, you might see high write latency statistics. For the QLE4060 and QLE4062 HBAs, you can use the QLogic SANsurfer GUI to change the value of the HBA Reserved TCP Config (Hex) option on the HBA Options tab. The value of this option is a hexadecimal number that looks similar to the following, where the third hex value (the third character from the right, representing bits 8-11) is a 1: BC00314C Change the 1 to a 2, so the new value looks like this: BC00324C Changing this value increases the initial size of the congestion window from 1 MSS (maximum segment size) to 2 MSS. There is no workaround for this issue for the QLA4050 or QLA4052 HBAs. Other Issues QLogic adapters may encounter problems if multiple logins are made to the same target using different CHAP credentials. If you are using multiple QLogic HBA ports with the EqualLogic Multipath I/O DSM, you might observe multiple sessions to a volume on the same PS Series array Ethernet port. This problem manifests itself as frequent iscsi target logout and login activity. To correct this behavior, uninstall the EqualLogic MPIO and manually create the required number of persistent iscsi sessions to a volume. Note: See the Host Integration Tools Release Notes for more information. PS Series Storage Arrays: iscsi Initiator and Operating System Considerations 3

8 Operating Systems The sections below describe considerations, issues, and limitations specific to host operating systems connected to PS Series Groups. Before provisioning storage to hosts running these operating systems, become familiar with the relevant content and, if necessary, make the required configuration changes. Microsoft Windows The following considerations apply when working with Microsoft Windows systems: Use diskpart Command to Set PS Volumes Online for Windows 2008 Server Core If you are running Windows 2008 Server Core, you must use the diskpart command to make the volumes on a PS Series group visible to the operating system, even though the volumes status on the group is already online. The following example sets a volume online and removes the read-only attribute, creates a single partition on the volume, and performs a quick format operation on the volume. Repeat these steps for each volume to which you want to connect. C:\>diskpart DISKPART> rescan DISKPART> list disk DISKPART> select disk=1 DISKPART> online DISKPART> ATTRIBUTES DISK CLEAR READONLY DISKPART> create partition primary DISKPART> format quick Use "Quick Format" to Format Thin-Provisioned Volumes on Microsoft Windows Server 2008 When you create a thin-provisioned volume and format it on a computer running Windows Server 2008 without using the quick format option, the formatting process appears to fill the entire volume, resulting in an alarm on the PS Series group that the volume has grown to its maximum size. To avoid this problem, do either of the following: Use the quick format option to format thin-provisioned volumes. If you already formatted the volume without the quick format option, use the Virtual Disk Service (VDS; part of the Host Integration Tools) to shrink the volume then increase the volume size on the group. Enable ICMP echo requests for iscsi initiators on Windows Server 2008 and Windows Vista To support group access from initiators running on Windows Server 2008 or Windows Vista, you must enable ICMP echo requests for ICMPv4, or for ICMPv6, if using an IPv6 initiator. See the following URL for more information: 4 PS Series Storage Arrays: iscsi Initiator and Operating System Considerations

9 Other Issues Microsoft Java Virtual Machine Version 1.1 No Longer Supported as of PS Series Firmware V3.2 release You cannot use this version of JVM to run the Manual Transfer Utility graphical user interface. You must install Java from Oracle Corporation. to run the utility. The Host Integration Tools Kit includes an updated version of Java. You can also download the latest Oracle JVM from the following website: Linux Red Hat 3.0 or Higher Enterprise Server or Advanced Server and Bundled iscsi Driver Use the default iscsi initiator configuration. No changes are required. Red Hat 5.1 and 5.2 Using IPv6 is not Supported Because of a problem with the Red Hat 5.1 and 5.2 iscsi initiators, using IPv6 with these Red Hat versions is not supported in this release. If you attempt to connect to a PS Series iscsi volume using IPv6 under Red Hat 5.1 or 5.2, the iscsi initiator fails to connect. No warning or error message is returned by this failure. Configuring Disk Timeout for Linux 2.6 Kernel SCSI Devices The default disk timeout setting for Linux 2.6 kernels is 30 seconds. The desired value is 60 seconds. Make the appropriate change for your operating system: For most Linux operating systems, use the following script to update the timeout value: for i in ls /sys/class/scsi_disk ; do echo "60" > /sys/class/scsi_disk/$i/device/timeout; done For Red Hat operating systems, use the following script to update the timeout value: for i in ls /sys/class/scsi_device ; do echo "60" > /sys/class/scsi_device/$i/device/timeout; done You can add the appropriate script to your system start up script. The location of the startup script varies with different Linux distributions; for example, /etc/rc.local, /etc/init.d/rc.local. If devices are connected after startup, run this script again to update the new devices timeout value. Solaris 10 Use the default initiator configuration. No changes are required. Note: By default, the Solaris 10 initiator automatically connects to all volumes it discovers. If it connects to a zero-length volume (such as the vss-control volume), it panics. To avoid this, make sure the vsscontrol volume on the group has access control records configured to prevent the Solaris initiator from discovering it. For example, make sure it does not allow unrestricted access. PS Series Storage Arrays: iscsi Initiator and Operating System Considerations 5

10 NetWare To adjust the timeout value for NetWare iscsi volumes: 1. Log in to NoRM (Novell Remote Manager) at the following address, with the administrator username and password: 2. Select Storage Services > iscsi Services. 3. Select Properties. 4. Change the Keep Alive Timeout (seconds) value to 300, and click Apply. 6 PS Series Storage Arrays: iscsi Initiator and Operating System Considerations

11 Related Documentation and Customer Support PS Series storage array documentation includes the following: iscsi Initiator and Operating System Considerations. This document. Provides recommendations for connecting iscsi initiators and host operating systems to PS Series arrays. Release Notes. Provides the latest information about PS Series arrays. Installation and Setup Guide. Replaces the QuickStart guide. Describes how to set up the hardware and start using PS Series arrays. Group Administration. Describes how to use the Group Manager GUI to manage a PS Series group. This manual provides comprehensive information about concepts and procedures. CLI Reference. Describes how to use the Group Manager command line interface to manage a group and individual arrays. Hardware Maintenance. Provides information on maintaining the storage array hardware. If you have a valid service contract or an array that is still under the first year of warranty, you can download documentation and firmware, search the Solutions database, and view FAQs and Technical Reports. You can also submit a support request (Log a Case) from the website. To access the customer support website: Open a browser and go to support.dell.com/equallogic, click Login and log in to a support account. If you do not have an account, create one by clicking Request a Customer Account under the login prompt. Contacting Dell For customers in the United States, call DELL ( ). Note: If you do not have an active Internet connection, you can find contact information on your purchase invoice, packing slip, bill, or Dell product catalog. Dell provides several online and telephone-based support and service options. Availability varies by country and product, and some services may not be available in your area. To contact Dell for sales, technical support, or customer service issues: 1. Visit support.dell.com. 2. Verify your country or region in the Choose A Country/Region drop-down menu. 3. Click Contact Us. 4. Select the appropriate service or support link based on your need. Choose the method of contacting Dell that is convenient for you. PS Series Storage Arrays: iscsi Initiator and Operating System Considerations 7

12 8 PS Series Storage Arrays: iscsi Initiator and Operating System Considerations