Adaptec's ISA1500 Storage Array Stumbles, But Delivers

Beta Bugs

As I painfully discovered, the default installation options for Microsoft's iSCSI Services will cause the iSA1500 automation software to fail--a fact the beta documentation overlooked.

In the course of testing, the ASM interface also failed when I was configuring or monitoring the iSA1500 and the attached test servers. The only remedy was to reinstall the software agents and delete the configuration database, which did not result in any data loss, but the time loss was measurable.

I spent several days troubleshooting these problems, and though Adaptec was able to reproduce them, it could not correct them until after our tests had been completed. Adaptec says all these bugs were fixed before the product first shipped.

After initially configuring the device using a serial or keyboard/ VGA console, you can accomplish ongoing management with the ASM, which is installed on one management host during the initial iSA1500 installation.Assigning Storage

Before using the iSA1500 for the first time, I had to assign available disks to storage pools. The iSA1500 is more limited than a locally attached RAID controller--entire disks must be dedicated to a pool. Once the pool is defined, the iSA1500 formats the array, which takes nearly 24 hours for a 1-TB RAID-5 array.

The key differentiator and timesaver in Adaptec's iSA1500 is its "three clicks to a terabyte" automation tool. The ASM and ASM Agent cut the dozens of tasks usually required to connect an iSCSI host and target down to just three clicks in a Web interface.Logging Overload

The ASM provides centralized logging and control for both the iSA1500 and the iSCSI-attached servers. I was surprised that ASM captured not just storage-related events but the entire Windows event log from my servers, which needlessly complicates monitoring. This made at-a-glance error reporting nearly impossible, though clicking on specific events revealed more useful information. These limitations were not corrected in the software shipping with the iSA1500.

You can configure the ASM to send alerts of specific problems and their severity via SNMP or e-mail.

Despite the beta bugs I encountered, ASM's automation tools are the saving grace of Adaptec's iSA1500 platform. They save you the trouble of performing time-consuming behind-the-scenes configuration tasks, including setting iSCSI permissions on the Windows server and iSA1500 array, formatting the volume, assigning it a drive letter and making it available in Windows.

Adaptec's point-in-time snapshot and rollback feature provide a simple way to create online backups that can be mounted on a remote file server and backed up to nearline storage or tape.This feature lets your enterprise use its existing direct-attached tape solution to back up the iSCSI-attached array. The rollbacks worked flawlessly, restoring the data to the last snapshot image. Online volume resizing was equally painless.

Need for Speed

My benchmarks showed that the iSA1500 was capable of delivering 93 Mbps of read throughput over the Ethernet network. Write performance was significantly lower, coming in at a maximum of 54 Mbps. I discovered that read and write performance drops slightly when multiple hosts access the iSA1500 concurrently.

Although I was satisfied with the overall performance of the iSA1500, I was disappointed that I couldn't get more than about 1 Gbps of throughput from the dual-attached Gigabit Ethernet system. My test data showed that the biggest bottleneck was most likely the four-port RAID controller embedded in the unit, rather than the host system or the SATA disks.

Bottom LineDespite poor documentation and transient problems with the iSA1500 management interface, my overall impression of the Adaptec product is positive. None of the problems I experienced prevented me from completing my tests, and final documentation and release code should eliminate most of the issues I encountered.

Joel Conover, a former senior technology editor of NETWORK COMPUTING, is principal analyst for enterprise infrastructure at competitive intelligence firm Current Analysis. Write to him at [email protected].