I'm migrating VMs from my 3.5 cluster to my new 4.0U1 cluster using Converter Standalone edition. I've migrated quite a few, but haven't done any with RDMs because I'm not exactly sure how to proceed.
Do I need to be sure all the 3.5 hosts and all the 4.0 hosts can see the RDM LUN before I start converting? Is there any chance for corruption since both clusters would be seeing the LUN at the same time?
Or, do I convert over the VM, remove the LUN from the 3.5 cluster, then present it to the 4.0 cluster?
You will want to present the RDM LUN's to the 4.0 servers. ESX will lock the RDM LUN so only one VM can access the LUN at a time unless you have enabled shared mode on it.
Once the LUN's are there, migrate the VM's over to the new host using converter taking care not to select the RDM-based drives. Once you have them VM converted, power down the source, edit the "new" vm and re-create the RDM mapping. Power up and make sure the drive letter mappings are correct.
Oops, I assumed you were doing a hot conversion. If you do a V2V, I'm not sure if it will bring over the RDM mapping or create a .vmdk for the SAN drive.
What I would do is write down your RDM Mappings and delete from 3.5 guests. Migrate your VM's to the new ESX 4 hosts. Present the RDM storage to your new ESX 4 hosts. Then re-add your RDM mappings from what you wrote down. I write these down sometimes so I don't get forgetful