The IBM SAN Volume Controller (SVC) is a functionally rich storage virtualisation appliance. Its unique abilities allow it to sit in front of many of the common storage systems from the world’s largest storage vendors and virtualise the disks arrays behind it. To the host, it appears as if nothing has changed, but to the administrator it provides a great amount of flexibility that can streamline many common tasks. There are many benefits to this technology and the approach it takes. It can introduce many cost savings such as negating host attachment license costs, reducing functionality licensing costs, especially in multi-vendor scenarios, improving performance across the whole storage estate and easing migrations from one storage device to another. With the addition of the new IBM Flash Systems family of arrays, an extra dimension is added to the capabilities of the IBM SAN Volume Controller.
IBM’s Flash Systems are high performance, resilient, flash memory arrays. Designed to provide high IOPS and accelerate applications and business functions beyond the traditional limitations of spinning disks. However, one of the benefits of an all-flash system is that any data moved onto it will benefit from the boost in performance. Less commonly accessed data would traditionally reside on slower, ‘bronze’ tier disks and be infrequently loaded into cache and, therefore, reduce an expensive use of flash memory storage space. By pairing the IBM Flash System with an IBM SVC (or IBM V7000) and using the ‘easy-tier’ function, the IBM Flash System can become a large cache of persistent high speed memory that can be advantageous to all disks storage within a storage pool by moving hot data extents into flash memory. The application and, therefore, business critical response times can be decreased dramatically.
By analysing the data over twenty-four hours, hot data naturally migrates onto the faster disk layer. The effect is to smooth out what would otherwise be traditional data hot-spots on disk or RAID arrays. Depending on the characteristics of the application and data, the IBM Flash System can be an extension of the SVC cache memory or the cache can be disabled for write-through. This can be dictated on a LUN-by-LUN basis and can be advantageous in reducing the data path to what is, essentially, memory anyway and in certain circumstances improve performance further by removing a ‘hop’ into traditional memory cache.
The IBM Flash System can also present storage to a host system in the traditional way. Disk LUNs can still be provisioned and attached to a server as any other storage array can do. The advantage is that specific applications, particularly heavily utilised databases (e.g. large TSM databases) or batch processing routines can have true flash-based performance.
The IBM Flash System can also present storage to a host system in the traditional way. Disk LUNs can still be provisioned and attached to a server as any other storage array can do. The advantage is that specific applications, particularly heavily utilised databases (e.g. large TSM databases) or batch processing routines can have true flash-based performance.
The flexibility of a SVC and IBM Flash System pairing can be used to virtualise and enhance the capability of many storage arrays, from many vendors, not just IBM storage, bringing tiered storage and a wealth of functionality to disk subsystems that do not have the some of these capabilities natively. The SVC allows the connection of many simultaneous vendor disks technologies to take advantage of the IBM Flash Systems concurrently, and thus accelerating the whole storage estate.
Steve Laidler - Technical Consultant - Celerity Limited
For more information on IBM SAN Volume Controller (SVC) and IBM Flash Systems please contact your Celerity Representative or contact us at Celerity.
