If you’re using raw access to storage LUNs with VMWare, and you’re using Windows, you can use the LSI Logic SAS virtual SCSI adapter option and create virtual drives. This is better than using the Microsoft iSCSI initiator because you can edit the drive mappings with the machine powered off and you can clone the machine and easily redirect all of your storage before powering the machine on.
The correct driver to be using is the LSI SAS 1068 driver. You’ll need to make a floppy image using an image tool — if you’ve access to a linux box, just use DD to create the image and then mount it and write files to it. If you’re on Windows, the venerable WinImage and other utilities exist. Either way, you’ll need to rename the file with a .flp extension and mount it on boot in your Windows VM in order to load the driver to see the drives.
I’ve been getting some pretty darned good performance with that and iSCSI LUNs on my Solaris server. I haven’t (yet) put together a decent test and some metrics to back it, but the machines on raw device LUNs feel a *lot* snappier than the machines that are on a 400GB VMFS. A good basic tutorial with iSCSI and ZFS is here: Running ZFS Over iSCSI as a vmware VMFS store — but note that I’m using raw LUNs after not being happy with the VMFS performance with a half-dozen hosts doing heavy I/O.