Xserve RAID Shows Promise

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Apple Computer Inc. has taken its creative engineering to the storage world with the introduction of the Xserve RAID system, which has high potential but a limited audience, at least for now. Designed to complement Apples 1U (1.75-inch) Xserve servers, the Xserve RAID, which began shipping last month, provides powerful storage in a small 3U (5.25-inch) enclosure.

As it did with the rest of the Xserve line, Apple has tapped economical ATA hard drives to provide Xserve RAIDs storage capabilities. Other vendors take the more common (and more expensive) path of using SCSI and Fibre Channel disks. A fully loaded Xserve RAID unit with 2.52 terabytes of storage capacity, battery backups for the cache and dual 512MB RAID controllers costs $11,649—a bargain compared with most SCSI-based RAID units, which can cost double or triple that amount.

The Xserve RAID is targeted at applications where Apple has its greatest market strength, such as media production and editing, but it could also do well as a storage device to power file servers and other applications.

In eWEEK Labs tests, the Xserve RAIDs capabilities were impressive, but its Apple-only focus is disappointing because it could be an attractive storage option in Unix and Windows shops as well.

IT managers who need a comparable solution for Windows and Unix should check out Nexsan Technologies Inc.s ATAboy 2, which also blends ATA drives with Fibre Channel connectivity.

We hope that Apple will eventually see the light and support the use of the Xserve RAID unit in Windows and Unix shops.

The Xserve RAID connects to servers using 2G-bps Fibre Channel. The back of the Xserve RAID unit has two HSSDC2 copper connectors, but we would prefer the option of using either optical or copper connectors.

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The big problem with having only copper Fibre Channel connectors in the back of the Xserve RAID is that copper cabling must be used to hook up the unit to a Fibre Channel switch. As a result, the Xserve RAID unit cannot be placed very far from the switch, which could be a problem for sites that want to centralize storage on a site away from where servers are located.

The Xserve RAID has 14 drive bays controlled by two RAID controllers (each controller handles seven drives).

To create RAID sets with more than seven drives, we had to use software RAID to bind the two RAID sets together. Under this scheme, an IT manager who needed a 14-disk RAID 0 set would have to construct two seven-disk RAID 0 sets and bind them together with software RAID. Considering that this RAID system was designed to work with the relatively small, two-processor Xserve, having two separate controllers could be a more flexible option than having two clustered controllers in an active/active setting. IT managers could easily hook two servers to it (one on each controller) without having to buy a separate Fibre Channel switch to hook everything together.

The software management tools were fairly easy to use and provided a host of diagnostic information that could be used to manage multiple Xserve RAID units.

We liked the Xserve RAIDs management tools. The tools can be run on Windows and Unix machines using a Java Archive file. Because the management tools can be used on non-Apple machines, and because the Xserve RAID unit looks like any other Fibre Channel RAID unit (from a hardware perspective), the barriers to using Xserve RAID on other platforms are largely political, not technological. This means the Xserve RAID unit might be made available to other platforms, in much the same way that Apples highly successful iPod MP3 player eventually became available for Windows.

The Xserve RAID has redundant, hot-swappable power supplies and cooling modules for fault tolerance. The RAID controller modules can be replaced without rebooting, when no transactions are running. This means that IT staff can fix one side of the RAID without having to interrupt transactions on the other side with a reboot.

Senior Analyst Henry Baltazar can be reached at [email protected].