Be warned that if you use multiple vmdk's on more than 1 LUN, that you will end up with vmdk's with the same name.
This will result in failure of commiting snapshots of that VM. You will have to shutdown the VM and do the commit then.
I wish VMware would have allowed us to choose the name when adding an extra disk or just fixing this issue.
I would prefer to name the vmdk-files something MYVM_C.vmdk and MYVM_D.vmdk indicating the partition instead of MYVM.vmdk and MYVM_1.vmdk for example.