Applications running on iSCSI
A few years ago, many analysts predicted FC SANs would be reserved for business-critical applications such as transactional databases, while iSCSI would be deployed for less business-critical, front-office applications, file shares and Web services. But when talking to users from various-sized organizations, it's clear iSCSI deployments span mission-critical applications and less-demanding office applications.

"Our primary business app runs off a Microsoft SQL Server," says Mike Leather, network services manager at Safeway Insurance Group in Westmont, IL. "Our developers and database administrators were telling me that our disk I/O performance wasn't acceptable; that was because we were growing too big for the original solution [and] we needed to look at something else."

Leather looked at FC SAN storage, but was wary of the challenges and expenses involved. He installed an EqualLogic IP SAN (now owned by Dell Inc.) primarily for his SQL Server environment, but soon found he was using iSCSI for everything. "The whole thing started out for SQL Server and exploded," he says. "We are using the SAN for file storage, Exchange servers and our VMware environment."

Weiss Group's Santillo found that iSCSI will support all of his applications, whether they're business critical or not. "Our custom in-house customer relationship management [CRM] app, which was running on Fibre Channel, is being moved to iSCSI," he says. "We had six SQL Server apps on Fibre Channel, but [they] are now on iSCSI. And we're moving our two Exchange databases to iSCSI. The CRM app is going on the Xiotech box [which is iSCSI enabled]. We're also moving our file systems and unstructured data over to Xiotech," he says. "I needed enterprise-level reliability without the price." Santillo says his six-year-old IBM FC SAN will become "end-of-life'd. We're migrating everything off to iSCSI."

iSCSI initiators
In the early days of iSCSI deployments, almost no one expected iSCSI software initiators to prevail over dedicated iSCSI HBAs.

Adaptec Inc., Alacritech Inc. and QLogic Corp. originally marketed iSCSI adapters complete with features such as TCP Offload, which negates some of the overhead of TCP/IP. These adapters were expensive and often sold for as much as $750, which is four to five times the cost of standard Ethernet adapters.

"We use the VMware and Microsoft iSCSI [Software] Initiator, and we also use iSCSI and Fibre Channel HBAs from QLogic," says Chris Rima, IT systems supervisor at UniSource Energy Corp. in Tucson, AZ. "We've been decreasing the use of the Microsoft iSCSI Initiator because it's not as efficient as the VMware iSCSI initiator or the QLogic iSCSI HBAs. There's a higher cost associated with the QLogic HBA, but it's minimal compared to the performance gains we get."