cLVM

[JonB]

To dynamically create DRBD volumes we would need to use DRBD on top of LVM.
If I also wanted snapshot backups of the VM on DRBD we would then need to snapshot the LVM under DRBD which is not how vzdump/qmrestore is designed to work.

LVM snapshots still work, they are just a bit different than how these tools expect right now.

To solve the hot-stand by issue I always setup two DRBD volumes, then have half the VMs on node A with DRBD0 and the other half on Node B with DRBD1.
Very simple solution, not confusing or complex, only requires a little bit of planning and makes split-brain recovery simple.

The 2 DRBD volume setup makes it harder to move virtualmachines to the other DRBD volume if one needs that. And you have a harder time using 3+ hosts optimally because to balance the load you might have to move virtualmachines across DRBD volumes.

I do not like the idea of adding additional complexity just to solve a problem that is already easily solved.
Your idea has certainly got me thinking, maybe we do need to think about this more to come up with the best solution.

I do not think you provided the best solution, just a quickfix.


What if one has a multiple hosts setup and wants to move guests to a 2 node setup in times of vacation? weekends? or maybe just nights, to shutdown all but 2 hosts and save power?

 

[dietmar]

We improved our own locking mechanism in beta3, so it should be quite safe without clvm:

see https://bugzilla.proxmox.com/show_bug.cgi?id=49

Please test and report any issues.