To view the Report card.
FC-AL promises to move data at 100 MB per second in half-duplex mode and 200 MB per second in a full-duplex configuration. Enterprise networks that frequently move large chunks of data, such as a video editing or large-scale data-mining installation, could benefit from FC-AL's speed and duplex capabilities.

When we set out to find the state of the art in Fibre Channel drives, we found a lot of talk, but only a few products. Nearly every RAID manufacturer we contacted--including Digital Equipment Corp., Data General Corp. and Storage Dimensions--was hard at work on FC-AL solutions, but only three were able to deliver a product for testing: MegaDrive Systems, RaidTec Corp. and Symbios Logic. IBM Corp., which has entrench ed itself behind its Serial Storage Architecture (SSA) as an alternative to FC-AL, declined to participate.

At the time we tested, all of the vendors used Emulex's LightPulse PCI-based FC-AL card as the host adapter connecting the server to the array. On the array side of the fence, however, only Symbios Logic's MetaStor DS-20E RAID System offered an integrated hardware RAID controller, which was deployed on the RAID unit's backbone; the compromise made by Symbios Logic was to use Ultra/Wide SCSI technology within the RAID enclosure for disk drives and controllers. Both MegaDrive and RaidTec, on the other hand, deployed fiber controllers and disks throughout their RAID units.

MegaDrive's Aria and RaidTec's FibreArray shipped as "Just a Bunch of Disk" (JBOD)-based units--a bare-bones alternative to high-end RAID systems. Rather than relying on proprietary hardware or software, they use the RAID capabilities built into the operating system. With Windows NT 4.0, the RAID choices are quite lightweight. Yo u can create RAID Level 0 (striping), 1 (mirroring) and 5 (striping with mirroring), and perform some rudimentary fault-tolerance activities, but that's about it. Don't look for high-end management, intelligent algorithms that send data to the appropriate RAID level, or automatic management of defects.

Performance of these drives was much closer to Ultra/Wide SCSI (which is approximately 40 MB per second) than the promised 100 MB per second single-channel speeds. Early Fibre Channel adapters--notably the Emulex card shipped with these units--deliver a maximum 40 MB to 50 MB per second. You can come close to those speeds with Ultra/Wide SCSI without the fiber price tag. Additionally, it's not known yet if you'll be able to easily upgrade existing FC-AL adapters to later versions. Consequently, you should buy for distance or the ability to daisy-chain devices--but not for speed.

Symbios Logic's MetaStor DS-20E was the clear winner in our tests--despite the fact that it uses Ultra/Wide SCSI disks and co ntrollers in the RAID enclosure, deploying fiber only to connect between the server and the RAID. It surpassed the other arrays in performance testing, supplied a good set of cabinet-level fault-tolerant options, and came with an extremely sophisticated set of administration options built into its administrative software package. Better yet, MetaStor offers all this at an excellent price.

To download an Adobe Acrobat .pdf format version of the Fibre Channel Disk Arrays features charts, click here.