AoE (ATA Over Ethernet) is a very simple and lightweight protocol which does not rely on network layers above Ethernet, this makes AoE potentially faster than iSCSI, with less load on the host to handle the additional protocols, it also means that AoE is not routable outside a LAN. AoE is intended for SANs only.
In some perspective, it is more comparable to FCoE (Fiber Channel over Ethernet) than iSCSI. It export block devices (SATA HARD DISKS) over the network with a very high throughput when coupled with a quality Ethernet switch. A qaulity Ethernet switch can maximize throughput and minimize collisions through integrity checking and packet ordering.
In a typically implementation of AoE, you will need some dual-port Gig-E cards, a Gig-Ethernet switch and some disks.
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# Comparison of AoE vs iSCSI
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These are the following advantages of AoE over iSCSI
* AoE is cheap and simpler software stack. The advantage of AoE is that you don’t have the overhead of translating ATA to SCSI then back to ATA if you are using ATA drives. So there is a performance pickup.
* Server processing load for iSCSI is much higher than AoE for equivalent throughput. AoE can spare processing cycles. iSCSI requires TCP/IP and its requisite complexity.
* AoE is not a routable protocol. Therefore it provides you inherent security.
* AoE Ethernet frames are passed by standard switches.
* AoE and iSCSI both have initiator support for Windows and Linux.
Disadvantages of AoE over iSCSI
* If you need features such as encryption, routability and user-based access in the storage protocol, iSCSI is a better choice.
* AoE is not much suitable for critical enterprise applications. AoE is not as scalable as iSCSI or Fiber Channel when you consider location i.e., with Fiber Channel and iSCSI, you can scale your storage throughout. This is primarily due to the inability of AoE to route AoE traffic.
* ATA disks are not as reliable as their SCSI counterparts.