Just a quick tip here that shows the power of virtualization and the tools built around it. If you have data in a virtual machine disk file (vmdk) and you want to use a dedicated SAN lun instead, use vmkfstools -i to import the contents of the vmdk to the lun.
For example, suppose you have a disk called SQLDB.vmdk and you would like to put its data on a dedicated SAN lun, here is what you would type on the command line (from the folder where SQLDB.vmdk resides and on one line):
vmkfstools -i SQLDB.vmdk SQLDB-rdm.vmdk -d rdm:/vmfs/devices/disks/vmhba1:0:2:0
Before you run the above command, shut down the virtual machine that uses SQLDB.vmdk and create and zone a SAN lun appropriately. In this example, the SAN lun is identified by ESX as vmhba1:0:2:0. It should be the same size or larger than the original vmdk. The result of this command will be the creation of SQLDB-rdm.vmdk. That is actually just a mapping file. When a virtual machines uses such a mapping file (rdm) it will actually work with the SAN lun that is behind it, in this case vmhba1:0:2:0.
If the SAN lun is larger than the originial vmdk file, you can just boot the virtual machine and if it is Windows, use dispart.exe to extend the volume to the full size of the lun. Alternatively, you can use the GParted live cd I blogged about earlier to achieve the same result.
