I am looking for the least amount of down time to do the following:
Issue: One ESX Host running ESXi 4.0 (locally attached storage) with one VM running on it. This host needs to be updated to ESXi 5.1 in the least amount of down time for the running VM.
Possible solutions:
1) Use a temporary server install ESXi 5.1, bring it up on the same network, export the VM to an OVF. Import OVF into Temp ESXi 5.1 server, then upgrade ESXi 4.0 to 5.1, then move the VM off the Temp Host to the new 5.1 host.
(not sure if I can export from 4.0, then import to 5.1, any one know?)
2) Use a Temporary Server to install ESXi 5.1 and create a cluster. Add the ESXi 4.0 server, cold migrate single VM. Upgrade ESXi 4.0 to ESX 5.1, cold Migrarte VM back.
3) Export VM, Do an in place Upgrade of ESXi 4.0 to ESX 5.1.
If anyone has experience with how long any of these options (or any options that work better ) please let me know.
Best Answer
VMWare outlines this very clearly, as you've noted.
Download new ISO containing the ESXi 5.1 distribution. Burn it to CD. Insert into your powered-off server, boot and run the installer.
This method preserves your existing VMFS datastore and works without a hitch.
Trying to move your VM's off, exporting and all of that other stuff introduces many more potential failure points than just running the supported in-place installer process.
Once updated, you will want to update your virtual machine hardware version and the VMWare guest tools for each VM.