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One of the biggest pain points in SAN consolidation projects, and with tiered storage in general, is data migration. The challenge of getting data from one array or tier to another, with the least degree of user disruption, increases with heterogeneous source and target arrays. To migrate data between systems of the same array family, you can use replication or the migration tools that come with the arrays. Follstad used EMC's SAN Copy to get data from a Clariion FC4700 to a Clariion CX700 array. It copies complete LUNs at FC speed. "SAN Copy is a great tool to copy massive amounts of data," says Follstad.
Storage managers have been creative when it comes to data migration. From simple host-based file copies (see "
A storage consolidation analysis wouldn't be complete without looking at virtualization as a means of combining smaller storage arrays into a large virtual storage pool that's managed by a virtualization engine. The more smaller, heterogeneous storage arrays you have, the easier it is to make the case for storage virtualization. Besides the obvious data migration benefit, storage virtualization provides a single storage management platform for provisioning and managing your SAN storage. On the downside, however, virtualization isn't cheap and is still going through a maturing process with EMC, Hitachi Data Systems Corp. and IBM Corp. promoting three fundamentally different approaches to virtualization.
"The ultimate storage consolidation goal is having a single storage system that serves multiple purposes and has multiple personalities," says Tony Asaro, senior analyst at the Enterprise Strategy Group, Milford, MA. It needs to serve high-performance as well as inexpensive large-capacity volumes, block-based and file-based optimized storage, and should work with well-known protocols such as FC, IP, CIFS and NFS. Although this lofty storage goal is usually only partially realized today, virtualization seems to have the greatest potential to make this consolidated storage nirvana a reality in the not-so-distant future.
This was first published in December 2006