iSCSI & Virtualization: Happy Union or Mismatch?

Users' iSCSI deployments are going through the roof, with more and more firms seeking a cheaper alternative to Fibre Channel, but a question mark hangs over the technology's virtualization story.

A report released this week by analyst firm R.W. Baird found that both virtualization and iSCSI are growing in popularity among cost-conscious CIOs and IT managers. Some 90 percent of 101 respondents surveyed by Baird are using some form of virtual infrastructure, and more than half of surveyed firms have either deployed, or will deploy, iSCSI.

Despite this uptick, users are still working through the economics of iSCSI, according to R.W. Baird analyst Daniel Renouard. "Some end-users noted the cost advantage of iSCSI is not as great with server virtualization due to improved utilizations," he wrote in the survey summary, alluding to the fact that the cost savings of iSCSI could obviate the need for virtualization.

Other analysts are more bullish on the benefits of joint iSCSI/virtualization deployments. "We believe that iSCSI will be a preferred storage protocol to support the back-end storage in virtualized server environments," explained Brad Nisbet, program manager of storage systems at IDC, in an email to Byte and Switch this week. "We like Dell's acquisition of EqualLogic, who has done an excellent job at developing an iSCSI solution for this."

iSCSI, which is increasingly being touted by vendors as an alternative to Fibre Channel, has been gaining momentum over recent months. Increasingly, the technology is being pushed as a way for users to reap the benefits of emerging technologies such as 10-Gbit/s Ethernet.But the biggest benefit of iSCSI remains its cost, something which is seen as particularly attractive for smaller firms. Dell, which recently threw down $1.4 billion to acquire EqualLogic, is one of a number of vendors attempting to push iSCSI into SMBs.

Even with all this activity, R.W. Baird's survey revealed that some IT managers are concerned about the performance of iSCSI and virtualization for certain applications. Some survey respondents "felt iSCSI does not perform well with server virtualization due to high I/O loads," wrote Renouard, alluding to transaction-intensive applications such as databases.

This simply underlines the fact that users need to do their homework before deploying iSCSI, according to David Vellante, co-founder of the Wikibon user group. "Yes, there may be some performance issues in virtualized environments, but customers should still investigate this," he says. "I would think that the high I/O throughput, the database applications, would not be the best candidates for iSCSI and virtualization.

"If you're talking about super high-end, mission-critical applications, that's the domain of Fibre Channel -- iSCSI is not going to compete there," adds Vellante, explaining that there are software tools from vendors like Akorri that aim to resolve some of these iSCSI performance issues.

Despite the challenges posed by certain virtualized applications, Vellante feels that iSCSI is still a viable option for users. "I would think that the economics of iSCSI relative to Fibre Channel, particularly in small-to-medium sized businesses, is still compelling," he says.Have a comment on this story? Please click "Discuss" below. If you'd like to contact Byte and Switch's editors directly, send us a message.