Real Ethernet SAN, ATA over Ethernet (AoE), hasn’t received the media hype of Fibre Channel over Ethernet (FCoE), but those who use it understand how leveraging the power of Ethernet unencumbered by Fibre Channel can deliver a flexible high performance scale-out storage solution that is designed from the ground up for simplicity, and virtualization, with a 5-8x price performance advantage over Fibre Channel.
Here are 10 key facts about Ethernet SAN from Coraid:
1) ATA over Ethernet has been around for over a decade. It is an open standard protocol and is included in the official Linux kernel 2.6.11.
2) Coraid is the market share leader of Ethernet SAN storage solutions providing a family of Enterprise class scale-out storage arrays called EtherDrive®.
3) The AoE initiator breaks down I/O requests to match the MTU size of the Ethernet network with no encapsulation and sends I/O requests in parallel across all available links.
4) ATA over Ethernet is connectionless and doesn't use sequence numbers, relying instead on per-request tags to keep I/O straight.
5) Storage arrays are identified by target and LUN with "major.minor" numbers, and the network can scale with additional clients and targets to over 65,000 nodes.
6) Retransmissions are handled by the protocol, and tagging eliminates worries about out-of-order requests.
7) ATA over Ethernet traffic uses multiple initiators, network links, and targets without any special protocols or configuration.
8) There's no security in the AoE protocol itself: There are no session controls, so any client can read or write data to any storage system, though access control lists based on MAC address and "config string" are implemented.
9) ATA over Ethernet isn't routable, so it's limited in practice to local-area networks.
10) Practically any Ethernet switch can be used for AoE, just so long as it supports 9k jumbo frames.