VERITAS SANPoint Storage Appliance Overview of an Open Platform for the Implementation of Intelligent Storage Server

VERITAS SANPoint Storage Appliance Overview of an Open Platform for the Implementation of Intelligent Storage Server

Table of Contents Introduction...1 Block I/O and Block Servers...3 File I/O and File Servers...5 A Storage Server Supporting both File and Block Services...6 Storage Appliance System Architecture...7 Summary...8

Introduction Where in a SAN does VERITAS software fit? Figure 1: Storage clients (application servers), SAN infrastructure, and SAN storage pools This diagram shows the three parts of a SAN application layer with storage clients or application servers, the infrastructure layer (the network), and the storage pool (where the actual storage systems and drives are). The application layer where the storage clients reside is the location where the standard VERITAS products sit. This is the place for the VERITAS Volume Manager, the VERITAS File System, VERITAS NetBackup, VERITAS Cluster Server, etc. These products (e.g. Volume Manager) view the storage on the SAN from the perspective of a single application server. The infrastructure layer is where the switches, hubs, HBAs (host bus adapters), etc., exist. Managing in this area means managing zoning (VNETs for a SAN) and understanding where all the objects in a SAN are (discovery). This is where the VERITAS SANPoint SAN Access Layer interacts while it runs on the application servers. The storage pool area is the area for VERITAS SANPoint Storage Appliance software. This software runs on a CPU dedicated to managing the storage pool. When one can manage the storage pool, one has the facility to consolidate storage and easily manage the storage capacity allocation per application server (storage client). Note that the diagram above shows the situation for a SAN. The story is similar for a LAN in regards to the storage pool. Because the file system sits in the storage pool, some of the elements in the application view actually move to the storage pool. However, we still have storage clients and storage servers. 1

The Market Need for Consolidated Storage The amount of data that is used for applications has grown dramatically over the last few years. Market research firms suggest this will continue with estimates of 50% to 100% per year capacity growth. This continued growth in storage has many people looking for storage solutions that are easier to manage. A 1997 survey of Fortune 100 companies conducted by IDC looked at 3 storage topologies and found a single person could manage 7 times the capacity in a fully centralized case (centralized storage, servers in the same room) as they could with a fully distributed case (storage tied to individual servers, each in separate rooms). This means consolidated storage can save money and one of the most precious resources skilled IT staff. Centralized, consolidated storage needs to be even more reliable than distributed storage since a failure of the storage server will affect many more applications and servers. This is especially true for storage supporting orderprocessing applications including e-commerce. This means both data reliability (no loss of data) and data availability (applications always up and running). As data storage capacity will continue to grow, a system should be scalable in capacity and performance. So as one adds more storage to the system, there is a way to scale the performance provided by the storage. If scalability also includes the ability to reallocate storage, short-term needs (like month end crunches) can be addressed easily, saving critical applications. This also provides for the ability to repurpose the storage (which server uses and needs it?). The VERITAS software products presented in this paper are designed to address the needs for centralized storage. They enable the creation of a central pool of storage with the controls needed to make this central pool of storage easy to administer, reliable and scalable with the right level of performance for the tasks at hand. What does VERITAS SANPoint Storage Appliance software do? There are two versions of VERITAS SANPoint Storage Appliance. Both turn a computer system into an intelligent storage server. They currently run on SPARC-based systems, and are in process of being moved to Intel-based systems. The Block Server, or SAN Storage Server version, enables a computer system to take its storage and serve that storage onto a SAN as virtual SCSI disks. These virtual SCSI disks have many advantages for ease of management and consolidation of storage. The main customer benefits of using this software are: Ability to easily allocate and reallocate storage on a SAN (the right amount of storage to the right computer system at the right time). This can be thought of as repurposing the storage from the application server perspective. Ability to consolidate storage behind the SAN (managing the storage pool). This consolidation can be with pre-existing fibre channel or SCSI storage not on a SAN. One could then repurpose non-san storage and move it into a managed SAN environment. The file server, or NAS storage server version, is currently called the File Server Edition. Because it is an Edition, it is more Solaris-centric than the Storage Appliance. The File Server Edition provides high performance file storage services and print services on a network (LAN or WAN) with the following benefits: Because of its ability to grow and shrink files online, it also provides an easy way to allocate and reallocate storage on a LAN. It can also consolidate storage on a LAN or WAN, especially since File Server Edition can be run on very large computer servers to provide high throughput and high availability. It is possible to conceive of a combined file and block server, both working from a common storage pool to further consolidate storage and ease management. This may become a future option for Storage Appliance. Existing Methods of Delivering a Centralized Storage Server Mainframe storage systems provide centralized storage facilities. While expensive, these systems are highly reliable and available, scalable to high capacities, somewhat easy to manage, and provide sufficient performance for the designated applications. In some cases, managing these systems (like adding capacity) has required the intervention of a field engineer. In the fluid open systems environment, this may mean expensive monthly SE visits. 2

Many of these systems have been built with proprietary custom I/O buses for performance. In addition, proprietary RTOS architectures have been used for performance and reliability. However, using an RTOS means significant engineering is required to update the storage system to new technology like the latest network interface or the latest disk I/O protocol. In addition, a proprietary realtime OS (operating system) may have difficulty adapting to SMP (symmetric multiprocessing). SMP can be a significant performance boost to upper end storage servers by increasing the number of I/O operations the storage system can supply. Since standard operating systems like Solaris already support SMP, the Storage Appliance software supports SMP. One only needs to run Storage Appliance software on an SMP system. In contrast, disk subsystems for open systems have been more focused on cost and price/performance and on single server storage. With their sharp focus, they have not dealt with all the issues needed for storage in a single server environment. Technology Changes Enabling Centralized Storage Servers Built with Open Systems Components: Technologies continue to be upgraded so companies can continue to create higher performance and more resilient centralized storage servers with open system components. 1. Disk drives continue to increase in performance, with higher rotational speeds, faster seek access times and faster onboard caches. 2. I/O buses continue to increase in performance. PCI buses are now available in a range of performance from 33MHz at 32 bits to 66MHz at 64 bits. Beyond these enhanced PCI buses is PCI-X and Infiniband. Infiniband is a serial bus architecture with multi-gbyte per second bandwidth. 3. CPU speeds continue to increase. Since many I/O systems have the processor in the data path, each increase in processor speed means more I/Os per second for certain parts of the workload. We are currently at 1GHz speeds for Intel processors. 4. Memory is increasing in speed and decreasing in cost at specific capacity / performance points. This means fast memory will be available for system caches in system memory and for cache on RAID controllers. All of the trends above show that the hardware available for open system support is increasing in capability and performance. This allows us to consider the use of these components in intelligent storage systems with the right performance for today, knowing that the next generation products will provide the next level of incremental performance. This allows intelligent storage appliances to be designed and built quickly, based on industry-standard architecture and operating environment. This then supports the quick integration of VERITAS added-value storage services previously available only in host-based storage management software. A software platform for design and implementation of this new class of storage device is available from VERITAS under the family name Storage Appliance. Since Storage Appliance software can serve both blocks and files, they will be discussed separately below. Block I/O and Block Servers Storage devices are usually designed to provide data to servers using one of two methods, either block-level or filelevel access. Applications are either optimized for either type of I/O access and both types of I/O access are usually supported within a customer site. Block I/O is the I/O tied directly to the disks or RAID controllers. Block I/O is used when direct access to the physical drives themselves is required by the application. The client requests or writes the data to the block server (disk subsystem) using the starting location of the data blocks and the number of blocks to be transferred. The connection between the block server and the client or application server is a channel protocol like SCSI or fibre channel connected directly to disks or disk controllers (e.g. RAID controllers). Since SCSI and fibre channel are light weight protocols, they provide a low latency connection with high performance. 3

Many applications do work with files and file systems. The operating system or the application provides a file system to help translate the block locations into file locations. When a block server is connected to a client or application server, the application or OS translates the blocks into files using a file system running on the application server or client. The diagram below shows the system configuration when the file services are supplied by the storage client or application server. SAN or Block Server Storage Client File System Virtual Disk Mgmt SCSI/ Fibre Channel Disk System Figure 2: Diagram of a block server connected to an application server One of the major application categories using block I/O is the database with raw partitions. These database applications use raw partitions (raw disk) since they have developed their own application-based (not OS-based) file system optimized for performance. Other applications may also require direct connections to disk hardware (block I/O) for other reasons. These include Microsoft Exchange, Microsoft Cluster Server (MSCS) and Netscape Messaging Server. Each of these applications work with a direct connection to the disk system or block server and the file system again runs on the application server. A disk system with a RAID controller can be a very basic block server and works well in a single host environment. In a multi-host SAN environment, most RAID disk subsystems do not have the controls to make it easy to assign specific chunks of storage and dedicate it to each of the multiple hosts. Storage Appliance software, when run on a system in block server mode, enables that computer system to take its storage and project that storage onto a SAN as virtual SCSI disks. Because these virtual disks have a defined SCSI specification, they can be seen by hosts properly supporting fibre channel targets as standard SCSI disks. Benefits of Using Storage Appliance Software for Block Services Easy capacity allocation on a SAN due to advanced management features described below. Ability to consolidate multiple storage elements (JBOD, disk systems) behind a Storage Appliance-equipped server to improve storage administration. High availability provided with storage client mirroring using the VERITAS Volume Manager. Ability to manage multiple instances of Storage Appliance from a single administrative GUI. Password security with checksum encryption. SAN Network Serving Blocks or Virtual SCSI Disks Multiple levels of password security (read only, read/ write, administrator (administers/ assigns passwords). Ability to limit access of a single virtual disk to a specified host (via WWN). This feature is based on software running on the Storage Appliance so it works across operating systems. This feature is required when multiple NT hosts are connected to the same fibre channel circuit. 4

Ability to provide multiple access paths to virtual disks via routes or paths to HBAs to enable highly available configurations with failover and provide multiple paths for specialized applications. Cross operating system support (currently NT and Solaris, will be expanded to other versions of UNIX including Linux and HP-UX. This is based on the highly compatible SCSI specification of the fibre channel targets presented as storage (Virtual SCSI Disks). Ability to grow or shrink a virtual disk online Note that certain operating systems like Windows NT can be configured to enable this feature without requiring a reboot of the storage client. Ability to optimize resiliency and performance at the disk pool using various RAID levels supplied by the VERITAS Volume Manager (e.g. RAID 1, RAID 1+0, RAID 5, RAID 0) Ability to tune performance with multiple I/O caching policies. Policy-based event and performance management based on the use of VERITAS Volume Manager. High Availability Options One can create a SANPoint Storage Appliance with a highly available disk subsystem at the back end, using Volume Manager or a hardware RAID system. To provide higher levels of availability, one can use Storage Appliance in conjunction with Volume Manager at the Storage Client. This mirrored Storage Appliance configuration ensures continued operation even if the fibre channel path, the HBAs or any item within the Storage Appliance should suffer an interruption. All that is needed for this configuration is two instances of Storage Appliance and mirroring software on the storage client. There are a number of other options which exist or will exist for Storage Appliance, incorporating VERITAS Cluster Server (VCS) or VERITAS Storage Replicator for Volume Manager (SRVM). Call VERITAS for more details on these options, their availability and suitability to your application. File I/O and File Servers One well-developed architecture in the open systems community is the file server. A file server combines print and file services within a single storage server. Files are then presented to the outside world through a common network connection like Ethernet. This allows the file storage server to easily connect required storage through a common well-controlled file system interface and make these files widely distributed through standard network connections. Customers deploy file servers for applications where the following is true: 1. The applications can support a remotely mounted file system through a standard protocol like NFS (Network File System) for UNIX or CIFS (Common Internet File System) for NT. 2. The performance through the network connection like Ethernet serves the application well 3. Sharing access to the same file by multiple clients or application servers is required. The diagram for a file server is shown below: NAS or File Server Storage Client File System Virtual Disk Mgmt SCSI/ Fibre Channel Disk System LAN Network Serving Files Figure 3: Diagram of a file server connected to an application server 5

For UNIX file sharing, NFS is the protocol of choice. It was developed by Sun Microsystems over 10 years ago and therefore has the benefits of being well tested and widely implemented. Virtually every UNIX operating system supports NFS, including HP-UX, IRIX, Linux, AIX and SCO. This means one can use a single file repository for file access to all these flavors of UNIX. In addition, NFS clients have been developed for PCs, NT, NetWare, Apple Macintoshes and a number of mainframe operating systems like VMS. NT file sharing is well served by the SMB/CIFS environment. SMB/CIFS is the protocol to serve files to Windows clients. This environment has been implemented both in NT and in software or systems running outside the NT environment. The Samba (open source software) is interesting with the open source development efforts happening. Benefits of Using the VERITAS File Server Edition Note that the File Server Edition will evolve into Storage Appliance File Services with enhanced ease of use. This high performance file- and print-serving software provides the following advantages: Ease of administration in assigning storage to the hosts on a network with the ability to grow and shrink files online. Consolidated file and print services in a mixed NT (CIFS) and UNIX (NFS) environment. Consolidated management of the storage placed behind the storage server, allowing one to create very large storage servers with high performance. Uses the VERITAS File System with journal for quick recovery to any reboot. Snapshot (point in time) copy to enable stable image backup. Ability to administer across UNIX and NT environments with Samba (currently at level 2.06+), including encryption. Note that Samba in the File Server Edition is directly supported by VERITAS. Support for NT domains and DNS/NIS/NIS+ for easy network-based administration in both UNIX and NT environments. Support for advanced features in the Solaris operating system to boost performance for file serving like trunking. Write acceleration using VERITAS QuickLog technology to write data to log, converting random writes into sequential writes. High availability configurations using VCS with multiple active nodes for high throughput as well. A Storage Server Supporting both File and Block Services From the above discussions, there is a place for both file and block servers. If one could combine both file and block services in one storage server, TCO (total cost of ownership) would be reduced in organizations using both types of storage. This storage server could be used either as a file server, a block server, or as both simultaneously. This is can be done today by assembling a combined configuration of the File Server Edition and the Storage Appliance software suite. This suite would be built from the following components: VERITAS Volume Manager (VxVM), VERITAS File System (VxFS) and the VERITAS Virtual Disk Manager (VxVDM). The base package will have the following characteristics: Storage partitioning among pools of clients, user communities, and applications. This would be while serving either blocks or files because the three base components (Volume Manager, File System, and Virtual Disk Manager) can both grow and shrink (depending on the storage client s ability to respond to this). With these features, Storage Appliance will have extensive flexibility in the reallocation of storage resources. 6

High availability due to many features of the base components including File System Quick Reboot, multiple paths to data (Volume Manager and Virtual Disk Manager), and built in RAID functionality of the Volume Manager. This RAID function can be used either with hardware RAID or by itself, providing different functions in each case. Full high availability configurations will be built using VCS software. Centralized policy and event management of VxVM, VxFS and VxVDM. Quick I/O function adding extended large block performance for block transfers-based on writing directly to the disk through the file system. This feature works with the SPARC architecture only. Note that this feature is now integrated into the Virtual Disk Driver of the block server. VCS to provide high availability. Storage Appliance System Architecture The base configuration of the VERITAS SANPoint Storage Appliance contains capabilities provided by the VERITAS Volume Manager, the VERITAS File System and the VERITAS Virtual Disk Manager. A diagram with the system and software architecture is seen in Figure 4 below. All of the storage management requirements for the two classes of systems are the same, except for how the data is presented to the servers. This means one can use a common software and hardware platform for both file and block serving. This gives Storage Appliance the ability to lower TCO for customers even if the file server and block server are created as separate entities. The VERITAS SANPoint Storage Appliance architecture is based on off-the-shelf general purpose operating systems with high-performance I/O subsystems built on commonly available standard hardware platforms. The first versions use Sun s Solaris operating system on SPARC or Intel IA32 architectures. These two will provide the richest set of features to the system. Linux is the next consideration for an operating system and will be released based on when sufficient functionality is available. Figure 4: Software and hardware architecture VERITAS SANPoint Storage Appliance derives its basic disk and file management capabilities from VERITAS Volume Manager and VERITAS File System. The Volume Manager provides partition level allocation and software RAID. The VERITAS File System provides efficient I/O, fast recovery and integrated support for point-in-time snapshots (for the 7

File Server Edition). The VERITAS File System also provides quick recovery for the Block Server version. Note that functions within the File System (like Quick I/O have been moved to the virtual disk layer. Figure 4 does not show the VERITAS SANPoint SAN Access Layer for discovery and zoning services. This will be integrated in a future release. The RAID data protection and performance capabilities used for the actual storage devices (backing store) may be implemented in Storage Appliance using the Volume Manager directly, or may be provided by hardware RAID disk subsystems. Volume Manager could then be used in conjunction with hardware RAID for added flexibility and resiliency. Both channel-attached (fibre channel or SCSI) or PCI bus-connected RAID subsystems can be supported. Other VERITAS storage services and applications can be integrated into this base configuration. Figure 4 shows the Storage Appliance with both File Level (File Server) and Block Level (Block Server) pathways available to connect the data to the client hosts. It is possible to configure a single subsystem with to serve both blocks and files simultaneously. However, our initial view is that a customer s performance will be optimized by operating a single Storage Appliance platform in either file server or block server mode only. Note that this functionality is available today with the File Server Edition and the Block Server Storage Appliance. Customers who have both software suites in use in their facility (Block Server and File Server) will be able to lower their TCO by having the reduced training, spares and support costs of one hardware and software platform handle two types of data. Summary In order to combine the price, functionality and time-to-market benefits of commodity hardware and software with the efficiency of proprietary implementations, VERITAS offers its SANPoint Storage Appliance architecture. This scalable, extensible environment allows OEMs and integrators to incorporate best-of-breed integrated storage management and storage service functions with their hardware, providing a basis for deploying and evolving block-based or file-oriented storage access. This software will allow end users to access this same level of functionality through the VERITAS PSO Consulting organization. The major benefit is a consolidated point of management to make managing a centralized storage pool easy. Part of that management is the ability to assign the right storage to the right place at the right time. Being able to repurpose storage for use on a SAN can be a major benefit as many customers have storage they wish to redeploy in a SAN environment. Another key to centralized management is to have a rich set of storage management functions. This includes volume management, backup management, replication, SAN infrastructure, high availability management and various file system functions. In addition, one would like a set of tools for policy management of storage. These functions are all part (present or near future) of the rich library of software functions provided by VERITAS. They are therefore all candidates for integration into Storage Appliance software. 8

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