ProxMox Upgrade 3.X to 4.X

The upgrade from ProxMox 3.x to 4.x is not as simple as in the past where you could do one host at a time and then re-add them to the cluster or through the apt repository. I wont go through the process of upgrading hosts that are using local storage as that is well documented in the ProxMox wiki [HERE]. I will share how I rebuilt my virtual machines manually.

This Guide Assumes the following..... That you have shared storage for your Proxmox environment. I'm talking SAN and NAS, not saving locally and doing storage migrations every time you migrate. Also, that you have a backup of your VM data on storage that is physically separated as a very wise precaution. It doesn't hurt to take a snapshot of your images right before you start.

• First you will want to download the ISO and burn it to a disc or write to a bootable thumb drive.
• Next you will want to migrate all or at least your essential VMs over to one host.
• Now you will want to boot the empty host from the new ProxMox disk and install the newest version.
• Once the new host is up and running, add the shared storage location where your existing VMs are running on the old host.
• At this point you will need to create each VM manually with the same ID and drive size as the corresponding VM running on the old host.
• You will need to repeat the following steps for each VM

1. Shutdown the VM on the old host.
2. Navigate to the shared storage and rename the disk image to corresponding VM to match. (Note the 1 & 2 in the file names.)
3. Delete the "pseudo" disk image only after you have verified that the VM has booted successfully on the new host.

• Once you have all the VMs up and running on the new host you can now shut down the old one and install the new version of ProxMox on it.
• After that, just add the remaining host back to the cluster and migrate the VMs around to balance the load.