Four-Gig FC Smites IP

As a new version of Fibre Channel takes root, hopes for IP SANs are wilting on the vine.

After a rocky start, 4-Gbit/s Fibre Channel is on the move, and though it may take two years (or more) to make its presence felt in any significant way, it's almost guaranteed a spot on future SANs - a spot that just might have gone to an IP SAN just a few months back.

In this month's Byte and Switch Insider report –- 4-Gbit/s Fibre Channel: The First Step Toward the Future –- author Rik Turner explores how 4-Gbit/s FC made it back from the brink of demise just a few months ago, snarling the plans of IP fans worldwide, who wanted Ethernet-friendly 10-Gig, not 4, to be next on the storage menu (see Fibre Channel SANs: 4G or Not 4G?).

"The sector had a momentary infatuation with 10 Gbit/s in the fabric as a knee-jerk reaction to 10-Gbit/s Ethernet," Turner says. But that was before it became apparent that deploying iSCSI is not as straightforward as just putting an iSCSI HBA into the server and attaching it to disk or tape devices.

Indeed, most SAN vendors, while supporting iSCSI and offering products, acknowledge it's going to take time for the market to ramp up. Currently, only IBM Corp. (NYSE: IBM) offers an array with native iSCSI connections, thanks to an OEM deal with Adaptec Inc. (Nasdaq: ADPT). (See IBM Slips iSCSI Into SAN.) Competing iSCSI products from EMC Corp. (NYSE: EMC) and Network Appliance Inc. (Nasdaq: NTAP) provide add-on products that adapt iSCSI to fit their existing Fibre Channel arrays.Meanwhile, sales from startups like EqualLogic Inc. are still relatively small. And while there are devices that bridge iSCSI and FC SANs, some in the industry argue that for the price of these bridging devices, why not double FC speed and save a ton in cost?

Turner says 4-Gbit/s equipment will start life by replacing the connections between SAN fabric switches, or between disk drives and controllers in storage enclosures.

These are the places where speed is usually needed first; so it's no coincidence that the vendors that make controllers are the only suppliers that have made serious 4-Gbit/s product announcements: Applied Micro Circuits Corp. (AMCC) (Nasdaq: AMCC), Emulex Corp. (NYSE: ELX), LSI Logic Corp. (NYSE: LSI), and QLogic Corp. (Nasdaq: QLGC).

To make 4-Gbit/s FC appetizing to customers that may not even need it yet, these and other suppliers plan to make the price of the new kit as close as possible to 2-Gbit/s gear. Qlogic is even talking about putting the cost of 4-Gbit/s on a par with that of 2-Gbit/s, then lowering the 2-Gbit/s price to serve the SMB market.

As 4-Gbit/s ramps up in the fabric and within enclosures, vendors will be promoting 10-Gbit/s for interswitch-links.All this won't help iSCSI's cause: While iSCSI vendors can claim that no HBAs are required to run their kit, the Fibre Channel vendors will be able to counter that iSCSI is constrained to 1-Gbit/s until 10-Gbit/s is widespread. Their marketing approach will likely be "4-Gbit/s now, backward compatible and forward compatible with 10-Gbit/s –- or a forklift upgrade to Ethernet."

A kick in the shins for iSCSI. But for how long? Though most FC vendors have a clear plan to support 1-, 2-, and 4-Gbit/s in fabrics interconnected by 10-Gbit/s, they can't speak beyond that. The jury hasn't even convened on whether 8-Gbit/s will be the next Fibre Channel signpost, or whether 10-Gbit/s would be more convenient for incremental growth.

A practical approach to the problem will call for exploring the reasons for faster Fibre Channel. If speed and distance are among them, that could pose a problem for FC and an opportunity for IP-based SANs.

Ultimately, the growth of Fibre Channel at any speed depends on the future of storage networking, which is itself full of unanswered questions. For now, though, at least one question –- FC or IP? –-seems to have been answered, to the near-term detriment of IP.

— Mary Jander, Site Editor, Byte and Switch4-Gbit/s Fibre Channel: The First Step Toward the Future is available as part of an annual subscription (12 monthly issues) to Byte and Switch Insider