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<color #22b14c>**Restoring a Proxmox from its snapshots (zfs file system)**</color> \\

09.03.2025: pour résoudre le problème de mismatch hostid entre l'OS et rpool essager: <note tip><code># rm /etc/hostid
# zgenhostid
# zpool set multihost=on rpool
# zpool set multihost=off rpool
# zpool status rpool </code>
</note>


<note warning>Old stuff not working any more!! \\ 
See https://forum.proxmox.com/threads/proxmox-virtual-environment-backup-und-recovery-mit-proxmox-backup-server.89207/#post-406609 for another method</note>

Source: https://www.youtube.com/watch?v=6ayd2NHkBXk&t=931s :-X


 
====== Configuration: ======
Proxmox5, running only 2 mirrored SSDs à 240Go (pool zfs RAID1). \\ 
In this case Proxox runs on dataset rpool/ROOT/pve-1 and the VMs are on datasets rpool/data/VM#######. \\
Restoring the Proxmox is restoring "pve-1" and restoring the VMs.

====== Preparing tasks: ======
  *stop the VMs
  *if you can, make a snapshot of the entire pool "rpool" to get the current state of the OS and of the VMs and e.g. sending the snapshot to a FreeNAS if the necessary storage capacity is not available with a USB disk. From the Proxmox: <code>
# zfs snapshot -r rpool@complete
# zfs send -Rpv rpool@complete | ssh root@FreeNAS.domain.tld zfs recv -vF pool/backup/Proxmox </code>

====== Restore: ======

===== Starting point: =====
  *A fresh installed new Proxmox as zfs RAID1
  *The Proxmox installation usb stick.

The Proxmox OS and the VMs can be restored independently from each other. \\ 
As the restoring is made from a usb device containing the snapshots, I think that the easier way is to restore only the OS in a first time and the VMs in a second time after the system is running again. In this case a simple usb stick is sufficient.

==== Step 1: ====
Getting the snapshot of rpool/ROOT/pve-1  on the usb stick:
  * plug the stick into the FreeNAS, create a "restore" pool and send the snapshot on it:
  * <code>root@FreeNAS $ zfs send -pv pool/backup/Proxmox/rpool/ROOT/pve-1@complete | zfs recv restore/pve-1</code>

==== Step 2 ====
  * Plug the restore USB stick
  * Then start a normal installation of Proxmox with the installation stick. \\ 
  * When the screen about the condition of use is displayed, press Ctrl-Alt-F1 to swith into the shell an press Ctrl-C to stop the installer. \\ From this state, there is enough OS in live modus to manage zfs.     //This trick is magic, isn't it???// 8-)
<note important>the keyboard has the US layout!</note>
  * <code> zpool import</code> shows the pool recreated during the new install and the pool for restore from the USB stick. 
  * <code> zpool import -f rpool </code> <code>$ zfs list</code> shows the datasets created during the fresh installation of Proxmox, present on the RAID1 pool.


==== Step 3: ====
  * The next step will be get dataset "rpool/ROOT/pve-1" and mountpoint "/" available for the data to be restored: <code>
$ zfs rename rpool/ROOT/pve-1 rpool/ROOT/pve-2
$ zfs get mountpoint rpool/ROOT/pve-2
NAME              PROPERTY    VALUE      SOURCE
rpool/ROOT/pve-2  mountpoint  /          local      ### this confirms that rpool/ROOT/pve-2 is mounted on "/"
$ zfs set mountpoint=/rpool/ROOT/pve-2 rpool/ROOT/pve-2 ### or the mountpoint you want
$ zfs get mountpoint rpool/ROOT/pve-2
NAME              PROPERTY    VALUE              SOURCE
rpool/ROOT/pve-2  mountpoint  /rpool/ROOT/pve-2  local          ### => OK </code>
  *  import the pool "restore". \\ <code>$ zpool import restore</code>
  * Have a look to the datasets and cehck that the snapshot for restoration is present:<code>$ zfs list
$ zfs list -t snap</code> 
  * Now we copy the data from the "restore" pool into a new created rpool/ROOT/pve-1 and set its mountpoint on "/" <code>
$ zfs send -pv restore/rpool/ROOT/pve-1@complete | zfs recv -dvF rpool/ROOT </code> \\ The transfer of data should be visible.
  * When this is over:<code>
$ zfs set mountpoint=/ rpool/ROOT/pve-1     ##### It is possible that "/" is already mounted because Proxmox have already done the mounting automatically.
$ zfs get mountpoint rpool/ROOT/pve-1  ## will confirm </code>
  * Remove the  restore stick:<code>$ zpool export restore</code>
  * Have a look and reboot:<code>$ zfs list
$ exit</code>

==== Step 4: ====
I had some minor issues at the reboot:
  * device (= the "old" dataset for pve-1) no found but the boot process didn't stop here. In case of problems, use the function "boot rescue" of the USB-stick for installation
  * zfs: the first boot stops because the import of dataset "pve-1" must be forced by hand ("-f") the fist time because of having been mounted on another system (= the previous used temporary OS for restoring).
  * nfs: nfs was not working and there were some error messages during the boot. Another reboot solved it.8-)

After the OS runs: <code># update-grub2</code> and reboot to solve the error messages at boot up.


===== Restoring the VMs =====
Restore the disks of the VMs: \\ 
From the FreeNAS: <code># zfs send -pv pool/backup/Proxmox/rpool/data/vm-100-disk-0@complete | ssh root@proxmox.domain.tld zfs recv rpool/data/vm-100-disk-0 </code>
and so on...