Live migration to another cluster (even from 3 to 5)

[tapsa]

All old proxmox users know how frustrating it can be to migrate your enviroment from 3 to 4 or even to 5. Ad there is many many other reasons why you some times want migrate your vm's from cluster to another.

There is dirty hack for that.
- copy from your local machine authorized keys your public key to target enviroment.
- make directory path to your source machine /etc/pve/nodes/target/qemu-server/
- make directory path to your destination machine /etc/pve/nodes/source/qemu-server/

and then use that dirty totally unsafe script

#!/bin/sh
LOCALHOST="$(hostname)"
VMID=$1
REMOTEHOST=$2
/usr/bin/scp -r /etc/pve/nodes/${LOCALHOST}/qemu-server/${VMID}.conf root@${REMOTEHOST}:/etc/pve/nodes/${LOCALHOST}/qemu-server/
/usr/sbin/qm migrate ${VMID} ${REMOTEHOST} -online
/usr/bin/ssh root@${REMOTEHOST} mv /etc/pve/nodes/${LOCALHOST}/qemu-server/${VMID}.conf /etc/pve/qemu-server
/usr/bin/ssh -o 'BatchMode=yes' root@${REMOTEHOST} qm resume ${VMID} --skiplock
[ -d ./backup ] || mkdir ./backup
mv /etc/pve/nodes/${REMOTEHOST}/qemu-server/${VMID}.conf ./backup/

And use it with like migrate.sh id targethost

Yes this is hack and it will give errors to you. It is probably good idea to add more checks to that. Also note that in some cases that will leave migration lock to conf file and you need clean that.
Anyway this is just proof of concept that it is not quite hard to migrate vm from cluster to another and I think it is quite odd that there is no feature in proxmox it self for that.

 

[Nkuean Kiriz]

Is this method safe for a 'production' host? I want to transfer from an old cluster to a new single node. But, the new node is currently on production.

What I did before was just copy the /etc/pve/qemu-server/<vmid>.conf from the previous node to the new one, since I'm running the images on a shared NFS storage, then just start and stop the VM. But this creates a 1-minute downtime. I want to 'live-migrate' all of my old VMs with 0 downtime.

I also don't want to add the new node to the cluster, then de-cluster the new node. I heard that it was such a risky thing to do (CMIIW)

Thanks before.

 

[jmjosebest]

Hopefully they can implement, because it's not very operative to have to do this tasks by hand using backups.

In Proxmox v3 this option was available with the vzmigrate command. Unfortunately it was removed along with OpenVZ.

 

[andy77]

Hi @tapsa , this hack seems to not work any more as the qm command is telling

no such cluster node

 

[spirit]

proxmox dev are currently working on cross-cluster live migration, so I hope I'll be soon available.

 

[andy77]

Well the last message I read about that was on Jan 2021 so more then one year passed. Do you maybe have some update about their progress?