ESX Server, IP Storage and Jumbo Frames
Scott Lowe has written an interesting post about enabling jumbo frames for VMware’s software iSCSI initiator. VMware does not support this (yet) but it appears you can already enable it. For full details, check his blogpost.
A jumbo frame’s size is typically set at 9000 versus the standard size of around 1500. Setting the frame size (or mtu) to 9000 actually lowers the amount of packet processing (assembly/disassembly) by a factor of six. The overhead for ethernet packets also decreased because you send less frames. In general, you should see a performance increase of around 20 to 30%. Note that you have to enable jumbo frames on all levels of your infrastructure: the ethernet switch, the server and the storage box (e.g. NetApp, EqualLogic, …).
