Hi!
I have a TWO node cluster (NO HA!) with DRBD8 backed virtual disks.
Each virtual disk has its own DRBD8 instance and DRBD8 is running in single primary mode.
I wrote a Proxmox Storage Plugin to activate the DRBD8 volume and to make it primary only, when the VM is started.
Today I was testing fail-over scenarios and all worked fine till the point when only one node is booting, while the other is off. My test VM didn't start because the default expected votes in corosync is the number of nodes in nodelist. In my case 2. Because the other node wasn't seen, it reached never the expected node count and didn't start my VM.
After some googling I found a solution. I added "two_node: 1" and "expected_votes: 1" in the "quorum" section of /etc/pve/corosync.conf. With this configuration the single note was able to auto-start my VM.
Is there any impact on my cluster which I currently don't see and which might lead to a non functional cluster or other problems?
I could omit the "expected_votes:1" and use "pvecm expected 1" in case of an emergency situation also, but then it would need always manual intervention to get the VMs running when one of the nodes can't boot.
And yes, this is an unlikely situation in a centre but there could be a hardware fault (my machines are several years old already).
BR,
Jasmin
I have a TWO node cluster (NO HA!) with DRBD8 backed virtual disks.
Each virtual disk has its own DRBD8 instance and DRBD8 is running in single primary mode.
I wrote a Proxmox Storage Plugin to activate the DRBD8 volume and to make it primary only, when the VM is started.
Today I was testing fail-over scenarios and all worked fine till the point when only one node is booting, while the other is off. My test VM didn't start because the default expected votes in corosync is the number of nodes in nodelist. In my case 2. Because the other node wasn't seen, it reached never the expected node count and didn't start my VM.
After some googling I found a solution. I added "two_node: 1" and "expected_votes: 1" in the "quorum" section of /etc/pve/corosync.conf. With this configuration the single note was able to auto-start my VM.
Is there any impact on my cluster which I currently don't see and which might lead to a non functional cluster or other problems?
I could omit the "expected_votes:1" and use "pvecm expected 1" in case of an emergency situation also, but then it would need always manual intervention to get the VMs running when one of the nodes can't boot.
And yes, this is an unlikely situation in a centre but there could be a hardware fault (my machines are several years old already).
BR,
Jasmin