IBM also plans to come out later this year with a process for placing heavily input/output-bound applications, such as searches against large databases, directly within the data-storage system, thereby improving system performance.
Storage virtualization is a means of shielding applications from underlying physical storage systems. That provides greater utilization of disk arrays by creating a single data-storage pool out of heterogeneous systems.
Earlier this week Network Appliance Inc. upgraded its re-christened V-Series storage-virtualization system, giving it the ability to more easily connect to back-end disk arrays. EMC Corp. is planning to launch its storage-virtualization product, Storage Router, this summer.
IBM said that 1,000 customers, mostly small-to-midsize businesses, have deployed its SAN Volume Controller, a two-year-old storage-virtualization product that moves blocks of data between IBM and non-IBM systems, such as Hitachi and EMC. The typical size of a storage pool created by customers using SAN Volume Controller is between 50 and 100 terabytes, executives said at a briefing in Cambridge, Mass.
SAN Volume Controller switches I/O requests between different physical-storage devices, acting as a buffer between application servers and SANs. It simplifies information life-cycle management (ILM), the movement of files between fast, expensive disk arrays and low-cost media for data archiving for regulatory and internal requirements.
SAN Volume Controller supports SAN File System to facilitate ILM, said Andy Monshaw, IBM's general manager of storage systems. SAN Volume Controller requires SAN File System to keep track of only logical addresses, rather than physical addresses.
Oakwood Healthcare System, a health-care network, has been using SAN Volume Controller since November to create a virtual pool of 16 terabytes of storage for document management and other applications.
Oakwood is testing SAN File System to perform ILM, says IT technical architect Brian Perlstein in an interview. For example, SAN File System can be used to create a policy that files accessed within the past month are stored on disk, and files that haven't been accessed in 24 months are stored on tape. SAN Volume Controller creates virtual addresses so that the applications don't need to keep track of where the data is physically stored.
Oakwood considered using EMC's Legato storage backup system in conjunction with IBM's Tivoli storage-management system, but rejected the solution as unwieldy, Perlstein says.
SAN Volume Controller already has simplified database replication and system upgrades at the health-care network, according to Perlstein. Replicating databases stored on multiple physical devices used to require lots of CPU horsepower, entail multiple CPU cycles, and use lots of system downtime, he says. Using SAN Volume Controller, Perlstein simply creates one large virtual disk, which allows replication to be performed in the background, without affecting users.
Similarly, when Perlstein needs to swap out an older storage device, he simply plugs in the new device and SAN Volume Controller automatically copies data from the old device to the new one. It then redirects I/O requests to the new device without having to bring down any applications.