[ClusterLabs] Quorum when reducing cluster from 3 nodes to 2 nodes
RHAYDEN at CERNER.COM
Wed May 26 11:48:25 EDT 2021
I had a SysAdmin reduce the number of nodes in a OL 7.9 cluster from three nodes to two nodes.
>From internal testing, I found the following commands would work and the 2Node attribute would be automatically added. The other cluster parameters we use are WaitForAll and LastManStanding.
pcs resource disable res_app03
pcs resource delete res_app03
pcs cluster node remove app03
pcs stonith delete fence_app03
Unfortunately, real world didn't go as planned. I am unsure if the commands were ran out of order or something else was going on (e.g. unexpected location constraints). When I got involved, I noticed that pcs status had the app3 node in an OFFLINE state, but the pcs cluster node remove app03 command was successful. I noticed some leftover location constraints from past "moves" of resources. I manually removed those constraints and I ended up removing the app03 node from the corosync configuration with "crm_node --remove=app3 --force" command. Now pcs status no longer shows any information for app3 and crm_node -l does not show app3.
My concern is with Quorum. From the pcs quorum status output below, I still see Quorum set at 2 (expected to be 1) and the 2Node attribute was not added. Am I stuck in this state until the next full cluster downtime? Or is there a way to manipulate the expected quorum votes in the run time cluster?
#17:25:08 # pcs quorum status
Date: Wed May 26 17:25:16 2021
Quorum provider: corosync_votequorum
Node ID: 3
Ring ID: 1/85
Expected votes: 2
Highest expected: 2
Total votes: 2
Flags: Quorate WaitForAll LastManStanding
Nodeid Votes Qdevice Name
1 1 NR app1
3 1 NR app2 (local)
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