Serial Attached SCSI (SAS), the follow-on to parallel SCSI, is designed for high performance enterprise requirements and offers both the benefits of backward compatibility with SCSI and interoperability with Serial ATA (SATA), bringing enterprises flexibility and cost savings previously not possible for traditional storage environments.

SAS controllers are an excellent choice for adding storage to your server, because they are compatible with both high performance SAS hard drives and high capacity SATA drives. SAS controllers also provide for future expansion, as most cards support from 32 to 128 hard drives (the 9690SA-81 included) with the use of SAS expanders. You are also able to use longer cables with SAS as opposed to limitations of SATA.

AMCC’s Windows and Linux-supported 3ware 9690SA (£450) is a high-end SAS controller that raises the bar in terms of RAID performance and flexibility – it offers both internal and external SAS/SATA connectivity, so you don’t have to choose between SCSI or SATA. The low-profile PCIe x8 card is also available in a choice of four models: 8 internal ports; 8 external ports; 4 internal/4 external ports; 4 internal ports. We’ve taken a look at the 9690SA-81, which has 8 internal SAS ports. Regardless of which model you choose, all are powered by a 3ware RISC I/O processor and are compatible with industry standard SAS expanders to scale up to 128 SAS and/or SATA devices.

The supplied RAID software suite is also the same across the range, which assures configuration compliance with every 3ware controller, irrespective of its storage interface. The software also lets you create, delete, modify or rebuild arrays and add hot-standby drives to existing arrays. AMCC’s 3DM2 utility also allows the card to be accessed locally or remotely via a Web browser.

You can monitor the controller, a notification system issues e-mail alerts in response to warnings and errors, and a new feature displays a pop-up window showing the error. An optional Battery Backup Unit with integrated write journaling and remote battery mounting capability provides added data protection in the event of a power outage, while RAID levels 0, 1, 5, 6, 10, 50, and Single Disk are supported.

One of the most important performance traits of a good RAID controller is its ability to perform fast read and write operations on a variety of block sizes. Since the 9690SA-81 features 512MB of 533MHz DDR2 memory it handles sequential reads and writes to the array without breaking a sweat. Indeed, while the fastest SATA drives can push data at up to 150MB/s, the 9690SA-81 pushes data around at least double that. As for reads, there is an 80% speed increase over SATA. In our test, random reads and writes were equally fast.

SAS is the preferred interface for the direct-attach server space, SCSI’s former mainstay. SAS is for mission critical applications that require higher levels of availability and native expansion. SAS is optimised for the random performance requirements of the data centre. The 9690SA’s advanced RAID features, SAS connectivity, and powerful 3ware performance architecture make it the ideal SCSI controller replacement for data centre and Web server usage. It’s everything you ask for from a controller: quick, consistent and reliable. As an added bonus you get more cache compared to competing models from LSI Logic and Adaptec.