using drbd in a 2+ node cluster

[RobFantini]

I assume that we can set up 2 nodes with drbd .

Then in pve make it so that storage is only available to the drbd nodes.

And set up High Availability in pve for the kvm's using drbd.

In addition have multiple other nodes as part of the cluster.

Is that correct?

 

[term]

I think it is possible to do it that way. If you use HA, all of your vms would run on only one of the nodes at a time. You would need to set up fencing to enforce that.

 

[e100]

failoverdomains is how you control what HA things run where.
The storage can be marked Shared and you can select the specific nodes it is on in the GUI.

Yes you can have other non-DRBD nodes in the cluster.
In my 20 node cluster 16 are DRBD and 4 are local storage only, no problems.

 

[screenie]

Hi,

may i ask you how you have your DRBD setup configured?
you have one DRBD device over all 16 nodes or 8 two node DRBD devices?

thx,
Alex

 

[e100]

Hi,

may i ask you how you have your DRBD setup configured?
you have one DRBD device over all 16 nodes or 8 two node DRBD devices?

thx,
Alex

16 Two node DRBD volumes.
Each node has it's own DRBD volume that is replicated to one other node.

Server 1 DRBD volume replicates to server 2
Server 2 DRBD volume replicates to server 1

 

[screenie]

That means you have both DRBD in primary/secondary mode running?

If you have a VM in a LV on Server 1 running, can you migrate this single VM over to Server 2 or do you have to migrate all VM's on this DRDB volume over to Server at once and set DRBD to primary on Server 2?

Because i have only one DRBD volume in primary/primary mode on both nodes to be able to move VM's back and forth between my servers as needed;

 

[e100]

Primary/Primary
You can migrate just a single VM with no problem
I typically keep all the VMs on a single DRBD volum on one node, makes cleaning up from a split brain much easier.

See the wiki to understand why I have two DRBD volumes per node: http://pve.proxmox.com/wiki/DRBD#Recovery_from_communication_failure