If you have been paying much attention to developments in storage and computing infrastructure in the last few years, you have noticed a significant trend toward virtualization. Servers aren't servers any more, they are virtual machines. Tapes aren't tapes any more, they are virtual tape libraries like the IBM TS7650 ProtecTIER Deduplication Appliance. And in the area of disk virtualization, the most widely adopted approach is the IBM SAN Volume Controller (SVC).
Up until now, disk virtualization has been an enterprise-wide thought. Storage managers who are tasked with taking care of hundreds of TB's, and often PB's of disks have for years turned to SVC to help eliminate the pain of migrating data between arrays. For these administrators, disk virtualization with SVC has also helped provide a common set of management interfaces and proceedures across storage from different vendors, and has helped to create a common set of services like thin provisioning, snapshotting, and mirroring across different tiers of storage.
Not every storage manager, though, is responsible for PB's, or even hundreds of TB's of storage. Most administrators are just looking for an affordable and 'easy to manage' means of satisfying the next request for more storage on Exchange, or SAP, or... About a month ago, IBM introduced some important changes in its mid-range disk virtualization product, SVC EE, designed with these storage managers in mind.
Perhaps the best way to describe these changes is with a picture... (Click on the picture to enlarge)
One of the challenges with traditional disk arrays is that they are relatively inflexible. Think about it... the arrays that have a lot of function (thin provisioning, excellent snapshotting, mirroring, etc.) are generally large, monolithic things that can take up a lot of real estate and burn a lot of power before you get to the first byte of storage. On the other hand, the arrays that are more modular -- allowing incremental growth -- generally don't offer the best software capabilities. And what's more, all of them generally charge an arm and a leg for the software capabilities they do offer.
The important thing IBM did was to package its virtual controller software in an affordable form factor and price it in such a way that mid-sized administrators can build and grow their storage infrastructure modularly. Do you need more disk capacity for a new application? Add an IBM DS3400 SAS disk enclosure. Do you have plenty of capacity but just want some more performance or connectivity? Add an SVC 8A4 controller pair. Do you have plenty of performance but just want some more capacity for archiving? Add a DS3400 SATA disk enclosure. With this sort of modular approach to scaling, the incremental cost of adding capacity can be greatly reduced.
Regardless how you choose to grow your virtual disk system, there are a valuable set of services that are all included in the base software license (e.g. no extra charge). They include:
- Transparent data migration from other arrays in your datacenter to improve appliacation availability
- Thin provisioning so you can get more effective use out of your storage assets
- FlashCopy (IBM's name for snapshot copies) to cut down the time required for application backup and cloning. This is the newest addition to the list of included features. Prior to a month ago, SVC EE FlashCopy carried a separate price.
Although I have used IBM DS3400 disk encousures in my example, a virtual disk system of unlimited size can be constructed using any number of IBM DS3400, DS4000 or DS5000 family disks. SVC EE can also virtualize up to 250 disks from other IBM or non-IBM disk systems.
Lower incremental cost for adding capacity. Efficient SAS and SATA disks. A valuable set of software functions included in the base price. Common management from the smallest configuration to the largest. Would that help save some time and money?