How To Do Storage Virtualization Right
Virtualization can help you go supersonic with the speed of backup and disaster recovery, plus trim costs. But you will need to rethink storage management.
Storage virtualization comes in several forms, starting with the most established, array-based virtualization. Here, a vendor provides an expandable array, to which that vendor's drives can be added; management software virtualizes the drives so they appear as a common pool of data. You're typically locked in to one vendor's hardware but donâ¬"t have to worry about finger-pointing among vendors if something goes wrong, says Forrester Research analyst Andrew Reichman.
Providers of such arrays include Compellent, EMC, Hewlett-Packard, Hitachi Data Systems, Network Appliance (NetApp), Sun Microsystems and Xiotech. Reichman notes that several such array-based virtualization products, including those from Hitachi (also sold by HP and Sun) and NetApp, also support third-party storage arrays. The Hitachi array is "the only option for the high end," he says, while the others are designed for relatively small storage systems of less than 75TB.
The newer option, network-based storage virtualization, uses software or a network appliance to manage a variety of disk drives and other storage media. The media can come from multiple vendors, typically allowing for the purchase of lower-cost drives than the all-from-one-vendor options. This lets you use cheaper drives for non-mission-critical storage needs and allows you to reuse at least some storage you've accumulated over the years through mergers and acquisitions, says Ashish Nadkarni, a principal consultant at the IT infrastructure consulting and services company GlassHouse Technologies.
Providers of such network-based storage virtualization (often as a component of storage area network (SAN) offering) include BlueArc, DataCore Software, EqualLogic, FalconStor Software, IBM, Incipient, iQstor and LSI. Current offerings tend to be for medium-size environments of less than 150TB, notes Forrester's Reichman.
The Hard Part
Storage virtualization's newfound flexibility and control does have risks. "The flexibility can be your worst nightmare...it's like giving razor blades to a child," says Wasatch's Engh. The issue that storage virtualization introduces is complexity.
Although the tools keep track of where the files' various bits really are, IT staff not used to having the data distributed over various media might manage the disks the old-fashioned way, copying volumes with partial files rather than copying the files themselves for backup. Or when setting up virtualized storage networks, they might accidentally mix lower- performance drives into high-performance virtual servers, hindering overall performance in mission-critical applications, notes GlassHouse's Nadkarni.
Virtualization tools aren't hard to use, but it's hard for storage engineers to stop thinking about data from a physical point of view, says PHNS's Walls. "Everything you thought you knew about storage management you need to not bring to the party," he adds.
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