ILTA White Paper
Infrastructure Technologies
22
I
n this age of e-discovery, virtual machine
snapshots and never ending flows of e-mail
messages, the prospect of gaining large storage
capacity at a low cost is very appealing. While
proprietary SANs yield great speed, features and
flexibility, their benefits come at a premium, and they
can require costly dedicated networks and and have
burdensome TCP/IP processing overhead.
Advanced technology attachment over Ethernet
(often written as ATA over Ethernet or simply AoE)
meets the need for large storage that is inexpensive,
fast and robust. AoE puts low level ATA disk commands
directly into Ethernet packets that travel between
the server and disk subsystem. While this sounds
complicated, AoE takes novel advantage of long used,
well understood and reliable technologies such as ATA
and Ethernet and commodity hardware such as serial
advanced technology attachment (SATA) drives to
create an elegant storage solution. In fact, the entire
specification for AoE, written by Brantley Coile, creator
of the PIX firewall, is just 12 pages long (http://www.
coraid.com/RESOURCES/AoE-Protocol-Definition).
Working with AoE is a bit like working with the iSCSI
(Internet small computer systems interface) protocol.
nathan c. smith mcKee, voorhees & sease, p.l.c.
Use ATA over Ethernet
to Create a SAN
