Adaptec Serial ATA RAID 21610SA review

Adaptec's name may be synonymous with SCSI RAID, but it has taken longer than 3ware to recognise the huge demand for low-cost storage that Serial ATA could satisfy. Nevertheless, it now takes the top spot for sheer port density, as its 21610SA RAID controller delivers 16 150MB/sec SATA ports.

Physically, it's around the same dimensions as 3ware's Escalade 12-port controller and has the SATA ports located in two groups of eight, with one group at the end of the card and the other inset into a cutout in the middle. It's worth noting there are several other significant differences between the 3ware and Adaptec products. The 21610SA also supports RAID0, 1, 10, 5, 50 and JBOD arrays and comes with 64MB of embedded cache memory. However, during testing we were advised by Adaptec that the cache memory can't be expanded and the card currently doesn't support a battery backup pack either. We also encountered problems: the controller hung while loading its kernel during boot-up, and we found that it refused to work with our 36GB Western Digital Raptor drives as used in the 3ware test. We discussed this at length with Adaptec, which stated it hadn't experienced any problems with any Raptor drives. It was as baffled as us as to why all six test drives failed to be recognised and, at the time of writing, investigations were still ongoing.

For testing, we swapped out the Raptors and replaced them with 200GB Maxtor DiamondMax Plus drives, which were recognised correctly and worked fine with the controller. The card's BIOS configuration screen comprises three main options for array creation and management, controller configuration and the same disk format and verify utilities as found with the SCSI controllers. We started by creating a two-disk RAID1 mirror and installed Windows Server 2003 on it. For local and remote management there's little to separate 3ware's 3DM 2 and Adaptec's latest Storage Manager utility, as both offer good levels of access to the controller, arrays and drives. Storage Manager provides plenty of information about physical and logical drives from its well-designed interface. It allows arrays to be created on the fly and new disks designated as hot spares or added to existing arrays. Error notification extends to sounding a buzzer on the card and sending a warning to a specified email address.

After we'd installed the OS, we added the StorCase drive bay to the test server with a further four Maxtor drives and configured them as a RAID5 array with hot-standby, taking a couple of hours to initialise. With Iometer at the helm, we saw average throughputs of 68MB/sec on the mirrored array and 124MB/sec for the RAID5 array, similar results to those returned by the Escalade. Processor utilisation was also down at under 8 per cent. With the array broken up into four separate drives, our tests reported transfer rates of 52MB/sec for one drive and disk worker and 156MB/sec for four drives and workers, which was also in the same performance ball park as 3ware.

Adaptec's card offers the higher port density and a slightly better cost per port to the 3ware alternative. Management facilities and performance are equally good. However, if you're looking for greater expansion options then 3ware is the better bet.

Author: Dave Mitchell