VM can't use DRBD resource as harddisk?

[davidisko]

Hi guys,

I have to copy VM to another host while it is running.
The VM disk image lays on LV in LVM group.
It has around 500GB so i can't afford the downtime while DRBD will sync the data over network. It would take few hours.

So here's what I did.

1. Pepared the configuration of the DRBD resource to use VM's LV disk image on node1 (created LV, and prepared config too on node2).
2. Stopped the VM.
3. Fired up DRBD resrouce and promoted it as primary so it could be writable.
4. Because you can't specify DRBD device in proxmox I started VM with DRBD resource using that long kvm command (... -drive file=/dev/drbd1,if=none,id=drive-virtio0,aio=native,cache=none ...).
Result: VM can't find/use that disk black screen on console.

Maybe the VM could use the LV directly but that could be very dangerous to data i think.
It should use DRBD resource insted.

The XEN hypervisor differs between used block devices with config syntax phy:/device/ and drbd:resource thereforce i think it has something to do with it.

Thanks for help

 

[e100]

If you can afford minimal downtime the procedure I posted recently would work well in your case:
http://forum.proxmox.com/threads/18436-Moving-non-shared-storage-VM-to-another-node

If you want to move the VM disk onto DRBD (to get it copied to other node) I would do this:
1. Setup DRBD according to the Proxmox wiki
2. Use Proxmox GUI "Move Disk" feature to move it onto DRBD

But that is just far too much work, I would just use lvmsync like I describe in the link above and accept the small amount of downtime.

 

[davidisko]

Thank you very much I'll try that.

But it would be also nice to find out why kvm can't run with drbd resource