IT Shops Expect iSCSI and Fibre Channel to Co-Exist

Published: August 1, 2006

by Timothy Prickett Morgan

If you look at the history of network connectivity, what you will see is that any protocol that comes up against Ethernet, no matter how good it might be initially, eventually succumbs to Ethernet and is supplanted. But that may not be the case until someone creates something I will call iFC, which is short for Internet Fibre Channel. Let me explain.

A few examples illustrate the point. In many ways, IBM Token Ring was technically a better protocol, offering higher bandwidth, better error correction. So what? In the long run, Ethernet improved, and because non-IBM shops--like the service providers who were responsible for building the Internet--chose Ethernet, that technology won. Similarly, InfiniBand was invented to create a switched fabric for connecting servers to storage and servers to each other, and it offered very high bandwidth and very low latency. But it never supplanted Fibre Channel light pipes between servers and storage, and as for system interconnections, so few vendors have come to market with InfiniBand products that they are relatively expensive and exotic, and Gigabit or 10 Gigabit Ethernet links are now popular at all but some of the largest supercomputing centers and for some clustered database implementations. And with the faster Ethernet links available today, Internet SCSI, or iSCSI, links to hook storage to servers is now giving Fibre Channel a run for the money.

But, at least according to the sentiments expressed in a survey of storage buyers done by Xiotech, a maker of storage area network (SAN) arrays for Windows, Linux, and Unix servers called the Magnitude 3D, it looks like Fibre Channel and iSCSI will co-exist for quite some time yet. Xiotech put together a survey, which got 110 responses, asking companies about their iSCSI and Fibre Channel plans. (I think 110 responses is kind of meager, but it is also typical of such surveys, so take the results as you will.)

The respondents in the survey said that while they expected iSCSI to increase from about 5 percent of their storage connectivity today to 19 percent two years from now, they also said that Fibre Channel would grow from 34 percent of their current storage connectivity today to reach 41 percent within that two-year span. Survey respondents said they would be less dependent on direct-attached storage two years from now, dropping from about the storage connectivity they have today (and dominated by SCSI links) to about a quarter of storage links.

iSCSI is a less expensive storage connectivity option right now, but on the typical Gigabit Ethernet networks it is used on, it also offers much lower performance than the 2 Gb/sec or 4 Gb/sec Fibre Channel links available today for SANs. So it is no surprise that survey respondents gave Fibre Channel a rating of 4.49 on a scale of 5 for performance, compared to 3.55 for iSCSI, and a rating of 4.35 for reliability and 4.16 for security, versus ratings of 3.49 and 3.41 for these same technological aspects for iSCSI. iSCSI got high marks for initial low price, with a rating of 3.55, versus 2.52 for Fibre Channel.