SATA HDDs Accessible over the Ethernet

Coraid's serial ATA over Ethernet solution aims for an improved management of Ethernet-based storage techniques. The technology was showcased at Southern California Linux Expo in the form of a SR1521T 15-drive tower that can be accessed by Linux, Mac and Windows machines.

Forget about SATA RAID arrays, the drives inside this tower can be configured in almost infinite ways. Jim Kemp, CEO of Coraid, claims that the individual drives, in each of the three rows of five drives, can be striped or mirrored with any other drive. However, the tower system provides RAID 5 and hot-spares configuration support, should users still need them.

As with any RAID array, information is stored on each drive so the drive's position inside the tower becomes irrelevant. "You can take all the drives out, jumble them and pop them back in - and it still remembers which ones are striped or mirrored," said Kemp. Common RAID-arrayed devices usually require the drive to be replaced in the same slot as the dead drive.

What does the Ethernet have to do with this? The back of the SR1521T has two Gigabit Ethernet ports along with three power supply units. Only two power supplies need to be running and the unit will sound an audible alarm if a power supply dies. In order to make SATA compatible with Ethernet specifications, Coraid further developed a proprietary small protocol called ATA over Ethernet (AoE), which was first introduced about three years ago. While the technology isn't that new, Kemp points out that the company has refined its products to include Serial ATA towers. The protocol uses the usual MAC addressing to find computers and special drivers have been written for each of the major operating systems currently in use (Linux, Mac and Windows).

Coraid's SR1521T tower retails for $4500, while a 3U rackmount version is about $4000. As always, the actual hard disk drives are not included, allowing users to configure the system in their own way.