ATA over Ethernet
SAN Recovery - ATA over Ethernet
ATA over Ethernet (AoE) is a network protocol designed to provide a simple and very low level transport mechanism for ATA commands to travel between a host and a hard drive. The protocol is developed by the Brantley Coile Company.
AoE does not rely on network layers above Ethernet like IP or TCP, so it cannot be accessed over the Internet or IP networks. Thus AoE is similar to Fiber Channel over Ethernet than iSCSI. It is also more lightweight. All these features add to its easy implementation, inherent security, and higher performance.
AoE has a number of advantages. AoE uses Ethernet and does not require the use of heavyweight transport protocol. AoE can spare processing cycles, while iSCSI requires TCP/IP that is highly complex. AoE has initiator support for Windows, Linux, and Mac OS X. AoE communicates with other devices using device MAC addresses, so it limits AoE to the local broadcast domain.
However, compared to the more supported iSCSI, AoE is not that cheaper especially considering the outstanding resources behind it. It is not as scalable as iSCSI or Fibre Channel. AoE is not enterprise-ready yet. Also, ATA disks are not as reliable as their SCSI counterparts.
The AoE protocol finds application in host-based cooperative locking. When more than one AoE initiator is using an AoE target, they need to communicate and avoid interference with one another. The config string feature of AoE helps in determining the access of particular hosts.
