There is an interesting blog over at blog.wilmsenit.nl comparing NSS disk performance on VMWare VMFS vs RAW disk access (RDM).
Surprisingly for NSS there is a big performance drop when using VMFS in combination with iSCSI.
Bottom line:
If you want to run OES / OES2 Linux NSS on VMWare ESX... Stick to using RAW disk access for the OES guests, also when running a fiber based SAN.
Next to the consideration to use RDM for the NSS volumes, if you are running OES2 SP1 (and SLES 10 SP2 *32 bit*) also check out how VMI can benefit your servers performance!
Read Michael's full test results here :