ATA over Ethernet

AoE [1], [2] is a recent protocol developed by Coraid.

ATA over Ethernet is a network protocol registered with the IEEE as Ethernet protocol 0x88a2. AoE is low level, much simpler than TCP/IP or even IP. TCP/IP and IP are necessary for the reliable transmission of data over the Internet, but the computer has to work harder to handle the complexity they introduce.

Users of iSCSI have noticed this issue with TCP/IP. iSCSI is a way to send I/O over TCP/IP, so that inexpensive Ethernet equipment may be used instead of Fibre Channel equipment. Many iSCSI users have started buying TCP offload engines (TOE). These TOE cards are expensive, but they remove the burden of doing TCP/IP from the machines using iSCSI.

An alternative to iSCSI, the AoE specification is 8 pages compared with iSCSI’s 257 pages.

The storage hardware sold by Coraid is very cost effective. The basic 1U four SATA disk chasis SR420 is 2000USD, and with the addition of four 750b SATA disks (say about $450) provides 3Tb raw for under 4000 USD in a 1U with RAID 0,1,5,10 or JBOD. This can be combined with their NAS Gateway the CLN20, to provide a reasonable local network storage system.

With Hitachi’s forthcoming 1TB disk, you get 4TB raw. Crazy!

Of course SATA is not the best for database system but if you have a low access archive type system, or a video silo then this is going to work well.

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