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ISCSI runs over plain, old Ethernet, which means you don’t need a separate Fibre Channel network. You don’t need host bus adapters. You don’t need Fibre Channel switches. You don’t need specialized IT staffers.
Bottom line: An iSCSI SAN is less expensive to set up and easier to run than a Fibre Channel SAN. Pure and simple. (Add your thoughts to one of our 50 greatest networking arguments: iSCSI vs. Fibre Channel.)
Of course, Fibre Channel runs at 4Gbps, while a typical iSCSI SAN would be running over Gigabit Ethernet, so there is that. But as 10G Ethernet becomes more prevalent in the enterprise, even that advantage will go away.
In fact, recent testing at the University of New Hampshire Interoperability Lab showed that iSCSI can successfully run over a copper 10G Ethernet fabric. The testing, which was conducted in October, drew 37 vendors who gathered to test out 10G Ethernet in a variety of scenarios. (Compare data replication and backup products.)
So, if you're building a new SAN or expanding an existing one – and who isn't these days – don't ignore iSCSI.
Last year, independent consultant Joel Snyder, who also does testing for Network World, caused a bit of a stir when he declared that Fibre Channel was dead. And Nik Simpson, a Burton Group analyst, called Fibre Channel a "dead technology walking" during a presentation at last year's Catalyst Conference.
Of course, Fibre Channel, as it pertains to its massive installed base, is far from dead. Companies with large investments in Fibre Channel will continue along the Fibre Channel path until something forces them to change course – either the need for an upgrade of existing gear as it ages, or the need for an upgrade caused by changing business demands.
According to a recent IDC report, iSCSI only accounts for about a 3% share of external disk storage, and the research firm expects it to hit 20% by 2010. So, iSCSI certainly has a long way to go before it displaces Fibre Channel.
But the trend line is clear. The Enterprise Storage Group (ESG) recently surveyed IT execs who already had network-attached storage (NAS) deployed in their enterprise. Thirty-two percent said they plan on replacing NAS with iSCSI to some extent over the next three years, while 47% said they will keep their NAS, but will deploy iSCSI for new buildouts.
When ESG surveyed IT execs who already had a mix of Fibre Channel and iSCSI, 25% said they planned to replace Fibre Channel with iSCSI to a significant extent over the next three years, while 42% said they only use iSCSI for new storage demands.
The good thing is that it's not an all-or-nothing proposition. You can keep your NAS, keep your Fibre Channel, and deploy iSCSI where it works in your enterprise.
Snyder puts it this way: "Network World readers who want to be on the power curve should be buying iSCSI. Yes, probably, there are individual situations where a single 4G Fibre Channel interface for a particular application is better than iSCSI today. But for 90% of the people who want to buy SANs, the right answer is iSCSI."