iSCSI Sucks, but that's missing the point. It's cheap and it's easy.

I’m frustrated about the way many people seem to be looking at iSCSI. 

People keep comparing it with Fibre Channel. They point out that iSCSI is slower, and less mature, and less reliable, and less quality of service, and more variability in packet latency. And then they argue that – as a result – iSCSI won’t be replacing Fibre Channel any time soon. 

That’s like arguing – in 1983 – that PCs won’t catch on because they suck compared to mainframes. iSCSI isn’t about replacing Fibre Channel any more than PCs are about replacing mainframes. Maybe someday, maybe not, but that’s not the point right now. 

iSCSI is about enabling networked storage in areas where Fibre Channel is completely impractical. If you think about it, Networked Storage has almost completely replaced DAS (Direct Attached Storage) at the high end. Pretty much all high-end storage these days (EMC, Hitachi, IBM, NetApp) is network attached, either SAN or NAS. Yet there are still billions of dollars of DAS sold per year. iSCSI is about converting the low-end half of DAS to networked storage. iSCSI is "networked storage for the rest of us." 

iSCSI’s biggest success so far has been for Windows servers running Exchange and SQL Server. I also see iSCSI getting traction for Linux. Over time perhaps mid-tier UNIX and eventually maybe even high-end UNIX, but now we’re getting into the "iSCSI versus Fibre Channel" question that gets me so annoyed. 

The two key drivers for iSCSI are cost and simplicity. Simplicity is much more important, so let me get cost out of the way first. 

Cost: It’s true that competition with iSCSI is driving down Fibre Channel costs, for both switches and for HBAs, but it is very hard to compete against free. Every computer these days is networked, so iSCSI adds zero cost. You can buy an iSCSI HBA if you want to, but iSCSI makes the most sense where performance isn’t an issue, so why bother. (On the other hand, the existence of iSCSI HBAs is a great safety net if you do have performance concerns.) 

Simplicity: The big win for iSCSI is simplicity. When I talk to people who have just finished an iSCSI installation, they say, "It just worked." No new hardware to add and not much to configure. 

I had a chance to visit the CIO of the Kuala Lumpur police department in Malaysia – hardly a hotbed of high-tech innovation – and he had just finished installing Exchange on iSCSI. His comment?: "It just worked."