FC vs iSCSI: A Winner Emerges

Will there be a war between iSCSI and Fibre Channel? Or is something else going on behind the scenes something that will make that question moot in the foreseeable future?

Publicly, most storage suppliers say iSCSI and Fibre Channel can coexist; that's the point of FCoE, after all.

Or is it? While it's based on Ethernet, FCoE will require new equipment, including specially equipped switches and HBAs, as well as a series of network modifications.

These modifications include actual protocol revisions and additions to Ethernet, designed to simplify I/O for blade servers, which in turn are hosting increasing numbers of virtualized servers.

As Cisco's Claudio DeSanti, a leading developer of FCoE in the T11 committee of INCITS, told Byte and Switch a few weeks back: "FCOE as a protocol requires the same lossless behavior that underlies Fibre Channel." To make that happen, DeSanti and others are working on new congestion notification, enhanced transmission, and flow-control specs for Ethernet in the IEEE 802.1Qau, 802.1Qaz, and PFC groups, respectively.It adds up to a fresh take on Ethernet – one that both iSCSI and Fibre Channel will use inside the data center.

"The common relationship between iSCSI and FCoE is data center Ethernet or premium Ethernet," states analyst Greg Schulz of The StorageIO Group. "Data center Ethernet will support both IP and FCoE. On IP you can have NAS (NFS/CIFS) and iSCSI and FCIP for FC over distance. FCoE gives you FCP and Ficon on a local basis."

We'll go out on a limb here. While it's true that iSCSI adopters are reporting success in growing numbers, and while there's lots of interest in both FCoE and iSCSI, the underlying trend appears to be data center Ethernet.

Here, a Sun representative might say that any upcoming war will be between InfiniBand and data center Ethernet. But that's another story.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.