Dipping a TOE into iSCSI

Arthur Cole

So you finally got it together and invested in an iSCSI SAN to eliminate, or at least diminish, your storage woes. The problem now is that your storage traffic is riding atop your LAN, either on a VLAN or simply as more data on the network. Either way, you're not getting the kind of storage networking improvement you had hoped.


What you need, according to Computerweekly, is a TCP/IP Offload Engine (TOE), basically a piece of silicon on the Ethernet card that lets the network adapter shift iSCSI traffic to a local process, taking the heat off the host servers or LAN-designated computers. The CW article is a good place to start evaluating iSCSI TOE cards. There are only a few vendors with solutions at the moment, but there are a number of factors to consider, such as port availability and host interfaces.


One of the more talked-about pending systems, if only because so little is actually known at this point, is CebaTech's 10 Gbps CebaIP core technology. Initially targeted as a GZIP-based compression system, the company plans to add a full TOE by the end of the year. But that's about all they're willing to say at this point.


Chelsio is offering a TOE on its 10Gb PCI-X and PCI-E Ethernet NICs through the Terminator 3 ASIC, with the added benefit of customized register access. Basically, the device can offload TCP processing at the connection level, the server, the interface, or network wide. The setup provides full duplex, line-rate 10 Gbps with as little as 5 percent CPU utilization.


And even some server manufacturers are finding the offload engine to be a valuable addition. Dell's newest PowerEdge server, the 2970, comes with a TOE for use with Windows Server 2003 SP1. This is on top of the PCI-E slot and AMD's Direct Connect Architecture for even greater network optimization.


Don't get me wrong, iSCSI is an extremely compelling technology that goes a long way toward solving your storage woes. But a relatively inexpensive tweak of your network card could make it go a lot farther.

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