Storage virtualization and iSCSI don't mix

Immature products and low market share leave iSCSI SANs in the cold when it comes to virtualization

As more and more products enter the market, iSCSI is becoming an increasingly attractive alternative to FC (Fibre Channel) SAN technology. Not only is iSCSI cheaper than Fibre Channel, but the technology is less complex to implement. Because it uses the familiar IP network protocols, it simplifies the IT skill set needed to maintain the SAN. Thus, though it’s not as fast and has a lower maximum capacity than FC systems, iSCSI meets the needs of many small businesses and non-mission-critical enterprise storage applications, such as departmental file sharing and near-line data storage.

If you’re considering iSCSI and virtualization is on your storage road map, however, you may want to think again -- at least for the time being. The management tools that take advantage of storage virtualization to aggregate storage subsystems across a network are not yet mature enough to handle iSCSI SANs, says Brian Garrett, lab director at the Enterprise Strategy Group, a market research firm.

That’s why Corrections Corporation of America has held back deploying cheap iSCSI SANs to handle lower-priority storage, according to Brad Wood, the company’s senior director of enterprise technology operations. Wood says today’s storage-management software can’t handle iSCSI SANs well. For example, iSCSI doesn’t have a single facility to provide global names, as Fibre Channel does.

Kyle Ohme, IT director at online retailer, also struggled to deploy storage virtualization on iSCSI SANs. Even with help from vendors BlueArc and FalconStor, the difficult effort has led him to scale back his iSCSI plans.

One reason for the lack of tools is iSCSI’s comparatively small market share. Garrett estimates that there are maybe 10,000 iSCSI SANs in place, compared with hundreds of thousands of FC SANs. Plus, he says, most iSCSI deployments are in smaller enterprises that don’t use the tiered storage or storage lifecycle management techniques that these tools address.

“iSCSI SANs are not yet well supported,” says Mark Lewis, chief development officer at EMC, but he expects that to change as IP-based storage gains market share. The Storage Networking Industry Association’s SMI-S standard may help bring to the iSCSI and IP world the same storage-management capabilities that Fibre Channel and SCSI enjoy -- and a basis on which to translate among them, notes Roger Wofford, IBM’s storage virtualization marketing manager. Until then, even in environments where iSCSI and FC SANs are interconnected, the management tools will remain separate.

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