Suppliers Hype 4-Gbit/s FC

A flurry of product introductions has upped the profile of midrange 4-Gbit/s Fibre Channel SANs. But it's getting tough to tell hype from help.

EMC this week released the Clariion CX3 UltraScale series claiming to be the first-ever SAN system to provide "end-to-end" Fibre Channel connectivity. (See EMC Uncages 4-Gig Clariions.)

However, Engenio is also claiming an end-to-end 4-Gbit/s Fibre Channel SAN for midrange deployments, as are its OEMs IBM and SGI. (See LSI Expands 4-Gig Family.) iQstor also claims an end-to-end system. (See IQstor Unveils Array.)

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To complicate matters further, Xyratex says its 4-Gbit/s disk arrays are being packaged with HBAs or with others' controllers to achieve end-to-end 4-Gbit/s SANs. (See IQstor Unveils Array and Xyratex Launches RAID System.)

All this raises the question about what comprises an end-to-end 4-Gbit/s system and whether users should care.

On the face of it, end-to-end appears to mean the ability of a SAN system to run at full 4-Gbit/s on front-end host connections, as well as 4-Gbit/s to back-end storage.

One analyst, Greg Schulz of consultancy StorageIO, says five elements must be present for a system to be called "true and full end-to-end 4-Gbit/s Fibre Channel:

By these criteria, most systems today lack at least one of the above elements. At press time, EMC came closest to having them all, since as of today the company has shipped 4-Gbit/s FC disk drives with its new CX3 UltraScale wares. Xyratex has no controller; at press time, Engenio had not shipped 4-Gbit/s disk drives, though it has announced them and a spokesperson says shipment is "imminent."

But it may not matter whether a system has all the elements or just some of them. There is more to the end-to-end 4-Gbit/s story than just having a series of checklist items. Performance, compatibility with mixed 1- and 2-Gbit/s FC systems, the availability of data services software, the ability to support a mix of FC and lower-cost SATA drives, as well as the footprint of the system itself all come into play.

The key is how well it all works together to meet (or not meet) a particular user's requirements. "Look for effective performance from the server to the disk drives instead of focusing on just the number and speeds of ports and types of internal processors and buses," Schulz says.

Gauging how all the pieces of a 4-Gbit/s SAN system work together as a whole is particularly important given early adopter applications for end-to-end systems. These include database processing, where latency is an issue, or any situation that calls for large amounts of fast, cheap storage. Likely scenarios include broadcasting and video processing.

In cases like these, the ability of a system to support 4 Gbit/s to back-end storage may not be sufficient cause to buy it, if a system lacks the physical compactness to justify the investment. Indeed, footprint can be a differentiator, since users cite consolidation as a benefit of 4-Gbit/s FC. (See 4-Gig's About Consolidation, Say Users .)

So are end-to-end 4-Gbit/s systems catching on? Thus far, not a single vendor mentioned in this story was able or willing to provide a customer for comment, though all claim to have systems in the field.

Clearly, these user testimonials, when they surface, will be key to understanding the impact of end-to-end 4 Gbit/s. Performance testing in the real world will be part of this. Until then, claims for and against various aspects of these end-end-end systems will remain unproven.

Mary Jander, Site Editor, Byte and Switch

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