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This guide explains how you can set up an AoE target and an AoE initiator (client), both running Debian Lenny. AoE stands for "ATA over Ethernet" and is a storage area network (SAN) protocol which allows AoE initiators to use storage devices on the (remote) AoE target using normal ethernet cabling. "Remote" in this case means "inside the same LAN" because AoE is not routable outside a LAN (this is a major difference compared to iSCSI). To the AoE initiator, the remote storage looks like a normal, locally-attached hard drive.
This guide explains how you can set up an AoE target and an AoE initiator (client), both running Debian Lenny. AoE stands for "ATA over Ethernet" and is a storage area network (SAN) protocol which allows AoE initiators to use storage devices on the (remote) AoE target using normal ethernet cabling. "Remote" in this case means "inside the same LAN" because AoE is not routable outside a LAN (this is a major difference compared to iSCSI). To the AoE initiator, the remote storage looks like a normal, locally-attached hard drive.
So if I understand it right, you have a box with a disk/partition/whatever, and you export it kind of like NFS and that export is connected to by another machine?
Does this mean you could say, setup your fileserver with a nice big raid setup, then export partitions to your web server, print server, etc. to be used as storage on them with lower overhead than say NFS exports?
Not quite. It isn't a server/client setup; the terms are "initiator" and "target" instead (note the singular). Just like it's a bad idea to have multiple VM's mounting the same physical partition on a real disk, it's also a bad idea to have multiple initiators controlling one target. Multiple writers can stomp on one filesystem, with disastrous results.
AoE is basically a re-map of the AT Attachment command set into Ethernet. Because it doesn't involve the Internet protocol, it isn't "route-able" into other networks. And, the largest ATA packet can easily fit into an Ethernet packet, so the translation doesn't require expensive state-tracking the way IP (and TCP above it) do.
It's suited for high-availability cluster setups, where one machine at a time controls the target and others wait for fail-over. That one machine may serve NFS or CIFS or something else, giving a many-to-one client/server setup, but that should be on a different layer than AoE.
N.B.: This is what I have managed to glean; others may feel free to correct me.
It's more a replacement for iSCSI than NFS, really (hypothetically, AOE ought to have less overhead than iSCSI and therefore potentially better throughput.)
On the network layer, AoE does have less overhead. iSCSI is wrapped in TCP/IP, which by definition involves a longer code path between the disk protocol and the wire. But that also makes iSCSI capable of reaching farther, conceivably to anywhere on the Internet, where AoE is restricted to the local Ethernet.
I need to correct my first comment above. Some filesystems are specifically designed for multiple access, like OCFS and GFS. This would also make AoE an option for high-performance clusters, with multiple simultaneous access to the SAN.
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So if I understand it right, you have a box with a disk/partition/whatever, and you export it kind of like NFS and that export is connected to by another machine?
Does this mean you could say, setup your fileserver with a nice big raid setup, then export partitions to your web server, print server, etc. to be used as storage on them with lower overhead than say NFS exports?