VERITS File Server Edition Managing onsolidated File Servers for Performance and vailability
Table of ontents Introduction...1 The VERITS File Server Edition...2 onsolidating File Servers...3 File Server Performance with VERITS File Server Edition...4 Inherent performance benefits of the platform...4 onfigurable performance improvements...4 The QuickLog Performance ccelerator...4 Striping...5 Improving File Server vailability...6 Online storage administration...6 Implementing Redundant Storage Techniques...7 Implementing Failover with the H Version...7 Simplified dministration...9 Storage dministration Interface...9 onsolidating Windows and UNIX File Server dministration...10 Summary...12
Introduction Today s computer users expect instant access to data anytime and anywhere. For storage administrators, these expectations can pose significant challenges. ritical data resides not only in high performance database systems, but also in unstructured files on desktops and, increasingly, on shared file systems hosted by file servers. dministrators responsible for maintaining these file servers, whether for internal use or for external customers or partners, must do so in an environment characterized by: Growing storage demands Heterogeneous clients Numerous, fragmented servers serving different sets of clients High availability requirements (often 24x7) common scenario is that a company gradually adds file servers over time, with administrators eventually supporting multiple file servers running on different platforms and operating systems, such as Windows and UNIX. This can create an ongoing administrative headache, particularly when faced with continually growing amounts of data and low tolerance for administrative downtime. In this environment, file server administration is frequently an exercise in ad hoc troubleshooting and buying more hardware. Special-purpose file server hardware may improve performance, but at the cost of implementing rigid, proprietary systems that increase overall system complexity. This situation doesn t have to be so grim. We do in fact have the tools and products to improve file server performance and data availability on existing, commodity hardware, and to simplify the tasks of managing these systems proactively. VERITS Software has integrated and packaged these solutions into a software solution optimized for hosting file system data in file servers or messaging environments. The VERITS File Server Edition is a tightly integrated software suite that improves the manageability, performance and availability of file servers using Sun SPR systems. The File Server Edition supports both NFS and IFS file sharing, so you can consolidate file servers supporting mixed Windows and UNIX environments. nd it is built on VERITS Software s industry-leading storage management solutions. This paper describes the components of the File Server Edition product, then discusses how system administrators can use the product to improve the performance, availability and manageability of their file servers. 1
The VERITS File Server Edition The VERITS File Server Edition provides a packaged, integrated solution for improving file server performance, availability and manageability for both UNIX and Windows clients. The product components include industry-leading storage management solutions, integrated and optimized for the file server environment: The VERITS File System is a journaling file system that provides better performance and availability than the standard UNIX File System (UFS). The VERITS Volume Manager is a logical volume management solution that greatly simplifies volume management and supports software-based RID, including mirroring and striping for optimal performance and reliability. VERITS QuickLog is a specialized write accelerator for write-intensive environments. Samba is an open source solution for UNIX servers that enables Windows and UNIX clients to share files and resources across a network. n optional H (High vailability) version of the File Server Edition integrates the following components as well: VERITS luster Server (VS), a highly flexible and scalable application monitoring and failover solution. VS agents for NFS, IFS, and VERITS QuickLog. The VERITS File Server Edition integrates all of these products into a packaged solution optimized for file servers. single graphical interface supports file system and volume management operations, and VERITS Software supports the entire, integrated solution even the open source Samba component. 2
onsolidating File Servers Environments with multiple file servers can realize many benefits by consolidating them into a single server. These include: Reduced management overhead. One administrator can manage the consolidated environment; there is one set of backups, etc. onsolidated hardware investment (making more efficient use of powerful servers and storage) Reduced network traffic In a consolidated environment, reliability and availability are more critical than before, as outages affect greater numbers of clients. The VERITS File Server Edition makes server consolidation a viable solution because it provides an inherently more reliable and available platform than native UNIX platforms, and because it gives the system administrator additional tools to ensure the availability of data on the consolidated server. The High vailability version of the File Server Edition includes automated application monitoring and failover for environments with critical availability requirements. In environments with both UNIX and Windows clients, file server consolidation can provide better communication and file sharing between UNIX and Windows clients and simplify administrative tasks. The VERITS File Server Edition enables mixed UNIX and Windows-based file server consolidation using Samba, open source software for UNIX. Samba implements the ommon Internet File System (IFS), the remote access protocol published by Microsoft. Samba lets a UNIX system operate as a IFS file server for Windows systems. The support is completely transparent to the Windows clients because Samba speaks the same language as the Windows systems. There is no client software to install on Windows clients. The Samba server appears in the Windows Network Neighborhood for the Windows clients and the files can be mapped to drive designations as if they resided on a Windows file server. Samba also enables print sharing, name resolution, and authentication services. onsolidated UNIX/Windows environment using one SPR Solaris server with VERITS File Server Edition. s part of the VERITS File Server Edition, Samba is an ideal solution for integrating file servers in mixed Windows and UNIX environments. Samba has all of the strengths of an open source solution, including the collaboration, testing and enhancements of the worldwide developer community. VERITS Software participates in Samba development by submitting enhancements back to the Samba community. The File Server Edition integrates all of the benefits of the open source Samba solution with VERITS industry-leading storage management software and support. The Samba IFS Server runs on the VERITS File System, which provides significant performance and manageability improvements over running on UFS. The VERITS File System and Volume Manager products improve overall system availability and reliability, and the H version of the File Server Edition provides application-specific failover for the file server programs, reducing the risk of downtime in a consolidated environment. 3
File Server Performance with VERITS File Server Edition Whether you run NFS alone or the mixed NFS/IFS environment enabled by Samba, running these processes with the VERITS File Server Edition provides significant performance benefits over running on UFS. Inherent performance benefits of the platform The VERITS File Server Edition uses the VERITS File System (VxFS), a high performance, fast-recovery file system optimized for business-critical file server applications and data intensive workloads. UFS allocates space in fixed blocks. VxFS uses extent-based allocation, which provides better performance for most applications. n extent is one or more adjacent blocks of data in the file system. Files written in larger extents have less fragmentation and fewer indirect pointers than files written in the smaller, fixed block sizes of traditional UNIX file systems. Disk I/O can occur in units of multiple blocks, so applications spend less time waiting for the disk head to cycle to the next set of blocks. For sequential I/O, multiple-block operations are considerably faster than block-at-a-time operations. More information on the performance can be found in the VERITS File System Performance white paper in the Reference Library at the VERITS web site, www.veritas.com. onfigurable performance improvements Other benefits can be achieved easily with minimal tuning and configuration on the part of the system administrator. For example, the VERITS Storage dministrator, the graphical interface for the File Server Edition, provides a simple, graphical interface for identifying and removing I/O bottlenecks. The system administrator can also configure the QuickLog performance accelerator and implement striping techniques to further improve performance. These are described below. The QuickLog Performance ccelerator The QuickLog accelerator provides ongoing performance improvements for any write-intensive environment (such as IFS, NFS, or messaging servers) using the VERITS File System. It does so by enabling parallel updates to file data and the intent log maintained by the file system. The VERITS File System is a journaling file system it maintains a journal, or intent log, which speeds recovery after any outage. File servers and messaging servers typically have numerous small files with frequent creation and updates. This generates more logging activity to track the metadata (such as inode information) in the journal. With QuickLog, the file system journals can be kept on a separate, dedicated journal volume. This enables journal updates to occur in parallel with access to the file data, mitigating any performance impact of maintaining the journal. Together with extent-based allocation and striping capabilities, the File Server Edition provides NFS performance improvements of 110% over the standard UFS. VERITS has also tracked performance improvements of more than 10 times UFS in messaging environments, such as e-mail and news servers. (For more information, see the VERITS File Server Edition Performance riefs, available on the VERITS web site.) Multiple VxFS file systems can share the dedicated journal volume; QuickLog interleaves journal updates from multiple file systems to utilize the volume space most efficiently. 4
Like all of the Edition components, QuickLog is completely transparent to the applications and users that access it. In addition, it is tightly integrated into the overall solution using QuickLog requires only a onetime setup, and VERITS luster Server agents offer automated failure detection and failover for QuickLog. more detailed description of the QuickLog accelerator can be found in the File Server Edition: VERITS QuickLog white paper, available from the VERITS web site. Striping Disk striping speeds file access by interleaving a volume s data across two or more physical disks, reducing time spent waiting for disk head movements. With the VERITS Volume Manager, you can create striped volumes (RID 0), striping with mirroring (RID 0+1), mirroring with striping (RID 1+0) or striping with parity (RID 5) all at the software level, using commodity disk devices. Simple striping (RID 0) improves performance by interleaving data across multiple physical devices. This speeds performance, but has implications for availability. The failure of any device in the striped set leads to the failure of the entire striped logical volume. For this reason, striping is usually combined with either mirroring or parity checking, to provide redundancy and protection against device failure. Volume Manager supports two combinations of mirroring and striping (RID 0+1 and RID 1+0), as well as striping with distributed parity (RID 5). These combine the improved performance of striping with the data redundancy of mirroring. RID 1+0 is mirroring plus striping the volume is first mirrored, then each mirror is striped. This provides the speed of striping on writing each mirrored set. However, if there is a failure of a subdisk, the entire mirror must be taken offline and resynched to correct the problem. RID 0+1 is striping plus mirroring the volume is first striped, then each column of the striped set is mirrored. If the stripe is large enough to have multiple subdisks, each subdisk can be mirrored individually. This reduces recovery time in case of an error, as only the smaller stripe must be restored to recover from a physical failure. RID 5 combines the enhanced performance of striping with the increased availability provided by parity checking. Using the RID 5 specification for striping with parity, the parity information is distributed among the volumes in the striped set. RID 5 is useful for providing high availability with limited disk resources. RID 5 logs provide fast volume resynchronization after a disk crash. Whichever striping layout you choose, software-based striping is highly flexible compared with hardwarebased RID devices. For example, the devices in a striped set do not have to be of the same size and speed, and can contribute different amounts of storage to the logical volume. nd it is easy to add devices to a striped set or otherwise resize storage allocations. With this flexibility, you can optimize the performance of existing storage hardware according to system usage and requirements. 5
Improving File Server vailability The File Server Edition provides an inherently more reliable and available platform for file servers than native UNIX environments alone, as it is less susceptible to file system panics and restarts much faster after a failure. Reduced file system panics Disks, being physical devices, degrade over time. The larger the file system, the more frequently the system encounters bad sectors or other I/O problems caused by the physical disk device. The UNIX file system has a tendency to generate file system panics when it discovers problems, even failures in noncritical subsystems. The VERITS File System protects the UNIX environment from unnecessary file system panics. If it detects a problem, it isolates the problem without causing failures on the file system as a whole. This eliminates a relatively common source of UNIX file system outages. Journaling for fast file system recovery s a journaling file system, the VERITS File System provides much faster restart after a failure or outage than UFS. Writes or updates to the file system are tracked in an intent log or journal until they are written to the disk. If a failure does occur, the VERITS File System uses the journal to restore itself quickly to a consistent state. It replays the log record and completes any incomplete writes. This process takes only a few seconds, regardless of the size of the file system, and ensures data integrity. In contrast, UFS buffers file system writes to a cache. It then synchronizes those writes to disk. fter a system outage, UFS performs a file system check (fsck), which walks through the file system metadata, examining and repairing structures as necessary. This requires a full scan of the file system. s file systems grow in size, the time to restart takes longer and longer. ecause system administrators can perform storage administration tasks while systems are online and available, the File Server Edition reduces the planned, administrative downtime necessary to maintain production systems. In addition, system administrators can configure redundant storage configurations to further improve availability. Sites with critical availability needs can implement the High vailability version of the File Server Edition to provide automated application monitoring and failover capabilities. These features are described below. Online storage administration One of the key strengths of the File Server Edition is that system administrators can perform routine maintenance while the system is up and available. These administrative tasks include: dding disks Replacing faulty or slow disk devices Resizing storage allocations Defragmenting storage Reconfiguring disk devices (for I/O load balancing or new application support) Reconfiguring mirrored or striped volumes With native file system utilities, all of these basic operations require taking data offline. The VERITS File Server Edition performs all of these operations online, safely. The users will be unaware of the maintenance operations. 6
Implementing Redundant Storage Techniques For critical data, the system administrator can implement software-based mirroring to ensure that a disk failure does not result in a loss of data. dministrators can implement this mirroring on a volume-by-volume basis, depending on the nature of the data stored. Software-based mirroring is highly flexible. Mirrored devices do not have to be of the same size or type. mirrored device may be a logical volume composed of storage on multiple different devices. If one of the mirrored devices fails, the hot relocation capabilities of the VERITS Volume Manager automatically create a second mirror on free space. This prevents the performance degradation that can otherwise occur when one mirrored device fails. The VERITS Volume Manager supports the identification of hot spare disks. In case of failures, the software first attempts to use the hot spare disk to replace a failed disk. If hot spare disks are unavailable, any free space available is used to maintain redundancy. The data can be swapped to the new disk while the system is running. Implementing Failover with the H Version Disk mirroring protects against disk-level device errors. ut the file server application itself is susceptible to other kinds of errors, including application errors or OS errors. The File Server Edition/H includes the industry s most flexible and scalable solution for high availability, VERITS luster Server. VERITS luster Server monitors and manages application service groups groups of application services that must be migrated together in the case of a failure. pplication-specific agents monitor applications and automatically restart or migrate them to another server if a failure occurs. ny node in a cluster may run multiple service groups, which may fail over to different servers according to the rules created by the administrator. 2 2 2 1 D 3 D 1 D 3 D 1 3 D D ❶ 4 service, 3 node cluster in normal operation. ❷ Node 2 fails. On failover, its load is balanced across nodes 1 and 3. ❸ Node 1 fails, and all services fail over to node 3. Unlike traditional, point-to-point availability solutions, VERITS luster Server provides a highly flexible and scalable solution. The product supports up to 32 nodes with cascading and multi-directional failover. The VERITS File Server Edition/H includes luster Server agents for NFS and IFS (Samba). In the case of a failure, the luster Server component migrates these services to another server. UNIX-connected NFS clients will see no failure (but may experience a brief delay as the services migrate to the new server). Windows clients will probably also not experience any problems, as Windows NT automatically retries connections. However, some nervous applications may quickly retry and fail before the services can be restarted. In this case, the user will need to reconnect to the file server. 7
The system administrator defines the failover policies, and can manage all multiple clusters and nodes from a single, Java-based management interface. The Java -based graphical interface provides a view of the services, systems, and resources being managed. System administrators can use VERITS luster Server to migrate services manually to alternate servers this gives system administrators a way to perform offline management tasks on a system while keeping vital data and applications available. For sites with critical availability requirements, the File Server Edition/H provides a high level of availability with optimal flexibility and manageability. For more information on the luster Server component of the File Server Edition/H, see the VERITS luster Server white paper, available on the VERITS web site. 8
Simplified dministration Simplified administration is one of the key objectives for file server consolidation. The VERITS File Server Edition makes the file server environment much easier to administer and maintain over time by consolidating administrative tasks within a single graphical interface and automating application monitoring and failover activities. Storage dministration Interface The VERITS Storage dministrator is the integrated graphical interface for the File Server Edition. This interface allows one-step execution of common storage configuration tasks, most of which can occur while storage is online and available. It also provides a graphical presentation of storage bottlenecks and statistics. The Storage dministrator graphical interface simplifies storage management tasks. With the File Server Edition/H product, application-specific agents monitor critical processes so you don t have to. In case of a failure, the software automatically restarts or fails over to another server, according to the policies that you have defined. Intelligent software makes the task of managing these servers much easier. 9
onsolidated Windows and UNIX File Server dministration Most sites find that it is easier to manage one consolidated file server than multiple servers, particularly if you have both Windows and UNIX file servers. The Samba support integrated in the File Server Edition simplifies the joint administration of Windows and UNIX clients significantly. Some of the key features are listed below. uthentication Samba supports four levels of security: share, user, server, and domain. (It also supports guest access to specific shares, so that users can connect without providing a password to generally available information.) With share-level security, anyone who knows the password for a share can access it. Specific shares allow access to certain users this is user-level security. Using server-level security, Samba validates users and passwords through a separate SM server before granting access to a share. Using domain-level security, Samba becomes a member of an NT domain and uses the domain primary controller to authenticate users. Using this security scheme, the user does not have to supply a password each time they access another Samba share in the NT domain. Encryption/passwords When users log on to the file server, they must send their password. The File Server Edition supports both encrypted and unencrypted password authentication. (Whether clients send encrypted passwords or not depends on the client system. Windows 98 and Windows NT 4 with Service Pack 3 each require encryption.) Encrypted passwords are stored in a private directory on the file server. Only the root user should have read/write access to this directory. password synchronization option in Samba helps keep the server s version of the encrypted password synchronized with the client version, for cases when the password changes. ccess ontrol Lists (Ls) UNIX and Windows each use slightly different permission schemes. In each case, access to a file depends on the user s ID and the permission structure. Integrating UNIX files into the Windows NT domain security system requires some translation on the part of the file server. Windows NT identifies users with a Security ID (SID) a combination of the user ID on the machine and a machine ID. To map to this scheme, Samba combines the UNIX user ID combined with a machine ID generated by Samba, thus creating an SID for the NT domain server. Samba maps the standard UNIX user/group/world and read/write/executable permissions to the corresponding NT permissions. UNIX world maps to the NT group everyone, the UNIX owner is the NT user, and the UNIX group is the NT local group. Setting up users disk shares shared service or resource is called a share in Samba. Disk shares point to directories on the file server. dministrators can create separate shares on the server according to system needs, with read-only shares and writable shares. If users will have personal or home directories on the file server, then creating a [homes] disk share simplifies the process of managing and creating user directories. The administrator creates UNIX accounts on the file server for the Windows users who will connect to the server. If a user (for example, bfranklin) connects to the file server and requests the [bfranklin] share, Samba checks to see if one exists. If it does not, but if the user and password match in the local password database, then Samba automatically creates a [bfranklin] share in the [homes] share. Samba creates these directories automatically, and only as they are requested. 10
Printer sharing With Samba, Windows clients can access printers on the Samba server and its clients. There are two ways to configure printer sharing. dministrators can add information about each printer to share into a configuration file. reating a generic [printers] share automatically configures printer shares for each printer in the printer capabilities file. On the Windows client, the available printers will now appear attached to the file server in the Network Neighborhood. Once the Windows client has the correct printer drivers, it can print to any of the sharable printers. Naming In Windows, the NetIOS name server is called the Windows Internet Name Server (or WINS server). The WINS server resolves names to IP addresses. File Server Edition server (using Samba) can be the primary WINS server for the Windows clients on a network. File Locks To protect files from concurrent updates, Samba supports the traditional, file-level locking of the standard DOS and Windows/NT operating systems called Deny Mode. Supported deny mode locks are DENY_NONE, DENY_RED, DENY_WRITE, DENY_LL, DENY_F, and DENY_DOS. For example, if a client opens a file with DENY_WRITE, no other clients can open the file with write access (if the file wasn t open previously). If a client opens a file with DENY_RED, no other client can open the file with read permission. Opening a file with DENY_RED+DENY_WRITE prevents other clients from opening the file with read or write permission. If a client opens a file with DENY_NONE, then any other client can open the file with any permission. Oplocks (client file caching) Samba supports Windows/NT client caching called oplock opportunistic lock. When a client opens a file it can ask for an exclusive oplock, which implied that this client is the only one who can access that file. The server will verify that there aren t any clients who access the file and will grant the oplock if this is the case. This allows the client to cache the reads and manipulate the file locally (like locks), without accessing the server. If later another client tries to open that file, the server sends an oplock break to the previous client (who opened the file with a exclusive oplock) and waits until the client acknowledges that the oplock is broken. Samba also supports level II oplocks (or shared oplocks), which allow multiple clients to access the same file for reading. If the client asked for a an exclusive oplock during opening but the file is already opened for reading, the server will grant the client level II oplocks which implies that nobody writes to the file so the client can cache the read data. Should any of the clients who have a level II oplock attempt to write to the file, the server will issue an oplock break to all the clients who own level II oplock on that file. If a client asked for an exclusive oplock and another client has the file for exclusive oplock, the server sends a message to the exclusive oplock owner to downgrade its oplock to level II and will grant the requester a level II oplock. 11
Summary The VERITS File Server Edition combines intelligent storage management techniques (such as extent-based allocation and logical volume management) with industry-leading solutions for remote file access and availability to create a flexible, configurable software solution for hosting critical file servers. Using the File Server Edition, consolidating file servers is not only viable, it s easy to do, because the software creates a better platform for hosting file servers. nd with the integrated Samba support, it is no longer necessary or desirable to maintain separate file servers for Windows and UNIX systems. dministrators can simplify the system environment with a consolidated solution. With the File Server Edition, administrators have the tools at hand to optimize the performance and availability of critical data identifying storage bottlenecks, reconfiguring storage, and implementing mirroring and striping as necessary for performance and availability requirements. nd they can perform these tasks while data is online and available, minimizing any service disruptions. y applying these techniques with the industry s leading storage management software, the File Server Edition turns commodity hardware into high performance, industrial-strength file servers while decreasing administrative burden involved in maintaining and growing those systems. 12
VERITS Software orporate Headquarters 1600 Plymouth Street Mountain View, 94043 North merican Sales Headquarters 400 International Parkway Heathrow, FL 32746 800-327-2232 or 407-531-7501 407-531-7730 Fax Global Locations United Kingdom 0800-614-961 or 44-(0)870-2431000 44-(0)870-2431001 Fax France 33-1-41-91-96-37 33-1-41-91-96-38 Fax Germany 49-(0)69-9509-6188 49-(0)69-9509-6264 Fax South frica 27-11-448-2080 27-11-448-1980 Fax ustralia 1-800-KUP 61-(0)2-8904-9833 Fax Hong Kong 852-2507-2233 852-2598-7788 Fax Japan 81-3-5532-8217 81-3-5532-0887 Fax Malaysia 603-715-9297 603-715-9291 Fax Singapore 65-488-7596 65-488-7525 Fax hina 8610-62638358 8610-62638359 Fax Electronic communication E-Mail: sales@veritas.com World Wide Web: http://www.veritas.com 90-01074-910 2000 VERITS Software orp. ll rights reserved. VERITS is a registered trademark of VERITS Software orporation in the US and other countries. The VERITS logo, usiness Without Interruption and VERITS File Server Edition, File System, Volume Manager, QuickLog are trademarks of VERITS Software orporation in the US and other countries. Other product names mentioned herein may be trademarks and/or registered trademarks of their respective companies. Printed in US. March 2000.