HA groups

[jdl]

Hello,
I have a 3 nodes (PVE001, PVE002, PVE003) HA cluster running PVE4.1.
The following HA groups exist :
GROUP1 : PVE002,PVE001
GROUP2 : PVE002, PVE003
What will happen if PVE002 is down ?
Will the VMs HA-migrate to PVE001 or PVE003 ?
How could i obtain the following behavior :
if PVE001 down, move to PVE002;
if PVE002 down, move to PVE003;
if PVE003 down, move to PVE001 ?
Thanks

 

[t.lamprecht]

That depends on the group you use for the respective resource (a resource is a VM or CT which is HA managed).
If you set GROUP1 for a resource and PVE2 goes down it will migrate to PVE1 if you set it to GROUP2 it will move to PVE3

So use three groups with the tuples (PVE1, PVE2) ; (PVE2, PVE3) ; (PVE3, PVE1) and assign the resource as you want them,
e.g. if you want that one runs and PVE3 and migrates to PVE1 assign it to the third Group.

http://pve.proxmox.com/wiki/High_Availability_Cluster_4.x#HA_Groups

 

[jdl]

OK, perfect, thank you.
I had already read the wiki, but the behavior wasn't clear to me.
For instance, how is defined the behavior if only one group is defined, e.g. GROUP1, and this group contain PVE1, PVE2, PVE3 ?
I tried and it seems to be something like "first vm in HA group GROUP1 move to PVE2, then second VM in GROUP1 move to PVE3" and so on.

 

[t.lamprecht]

We try to balance out the recovering VMs to the remaining node, if all remaining nodes have the same amount it's quasi random.

Lets say, we have three nodes with each 3 VMs, one node fails, now each of the remaining nodes get one VM and the last VM can land on both nodes.

You can fine tune this behaviour with node priorities inside groups, meaning that you can assign each node in a group a priority (has do be done through CLI, GUI has not the option as its not often needed) and the ha manager tries to run the VM on the node with the highest priority available.