I have just started the process of migrating my datastores from VMFS3 to VMFS5 and am generally taking the following approach for each datastore:
* use Storage vMotion to move all VMs to another datastore
* delete the old VMFS3 datastore
* create the new VMFS5 datastore
* use Storage vMotion to move all VMs back again
I know that I could just upgrade them to VMFS5 however I believe that I would not have quite the full range of features of VMFS5 (e.g. sub-block size 64K) and my block sizes would range from 1MB to 8MB and I would prefer that I have them all identical "just because".
I've run into a small roadblock: I have a VM that I use for backups and it has a couple of 2000GB virtual disks. Each disk is in its own LUN. When I browse the relevant datastores I can see that there is just a single VMDK file in the VM's folder. To achieve my goal I was thinking that I could maybe detach that virtual disk from the VM, move it elsewhere, delete/recreate the datastore as VMFS5, then re-attach it to the VM.
Just wondering if there might be a different way of handling it? Or should I just drop the idea of recreating all the datastores and just upgrade them to VMFS5 ... its such a quick process ... and moving everything off, recreating, and moving the data back again is rather laborious.