TOE (TCP offload engine)
TOE technology aims to take the server CPU out of I/O processing by shifting TCP/IP processing tasks to the network adapter or storage device. This leaves the CPU free to run its applications, so users get their data faster.
TOES have been proposed as an answer to the increasing demand put on servers by gigabit connections. In data transfers, the system CPU acts as a manager of applications running on the server and a traffic cop for data transfers between the disk drive and requesting devices. The CPU must repeatedly interrupt application processing and reach into memory to get disk data. So each bit of I/O the CPU processes slows down application processing. As a company aggregates multigigabit links, even a server CPU running at 1GHz or higher has little chance of keeping up with demands for data.
The idea of off-loading TCP/IP processing from the system CPU to specialized hardware is not new for server network adapters or mainframe environments, but it is for storage devices and controllers.
And the need for TOE has become especially acute with the advent of iSCSI, a standard for the transport of block-oriented storage data over Gigabit Ethernet networks.
"Implementing TCP off-load in hardware is absolutely a requirement for [iSCSI] to become mainstream," says Steve Duplessie, an analyst with the Enterprise Storage Group research firm in Milford, Mass. "TCP is required to guarantee sequence and deal with faults, two things block-oriented storage absolutely requires. Running TCP on the server will cripple the server eventually - so bringing the function into hardware is a must."
Arun Taneja, another Enterprise Storage Group analyst, agrees. "If storage vendors' products are able reduce the amount of CPU processing by 50%, that's a huge advantage, considering the processing will be done thousands of times," he says.
From Storage on steroids, Network World Buzz Issue, 09/24/01.
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