All aboard for six gig SAS

The six gig SAS bandwagon is gathering pace, with Hitachi GST announcing a 6Gbit/s small form factor (SFF) enterprise drive and Atto announcing six gig SAS host adapters.

Originally the Serial Attached SCSI (SAS) interconnect ran at 3Gbit/s, but a second generation of the standard doubled its speed to 6Gbit/s, making it better able to cope with larger capacity drives and provide an alternative to Fibre Channel, generally running at 4Gbit/s as a device interconnect standard.

Unlike Fibre Channel controllers a SAS controller can manage both SAS and SATA (Serial ATA) drives, with SATA drives offering higher capacity than SAS, traded off against slower spin speeds.

Seagate and AMD demonstrated a 6Gbit/s SAS drive-host link earlier this month. Seagate and Fujitsu announced initial 6Gbit/s SAS drives in November. Now ATTO Technology has announced a family of five 6Gbit/s SAS Host Adapters, the ExpressSAS H608, H680, H644, H60F and H6F0, with support for up to 512 physical devices, and 16 independent lanes of 600MB/s connectivity for an aggregate throughput of up to 19.2GB full duplex.

Hitachi GST has introduced its second-generation small form factor (2.5-inch) enterprise hard drive, the 10,000rpm UltrastarC10K300, intended for use by rack-mounted servers and networked storage arrays. The drive is offered in 147GB and 300GB capacities and ships with a dual-port 6Gb/s SAS interface. Hitachi GST says the 6Gbit/s SAS interface improves signal strength over greater distances, enabling larger, more complex storage infrastructures than its 3Gbit/s precursor.

We're seeing here a future performance tier 1 storage array component which will be accompanied by tier zero solid state drives (SSD) for high transaction rate data, and tier 2 SATA drives for the capacity storage needs of the array. If SSD prices come down and reliability goes up, we might see SSDs starting to take over the performance SAS disk role in the future. ®