Could not log into web GUI while other node was shut down?

loneboat

Member
Jan 17, 2019
36
2
13
32
I have a 4-node cluster with nodes A, B, C, and D. I recently had to take nodes A and B offline to install a new NIC in them.

I wanted to watch their status on the web GUI of node C while I waited for them to boot back up, so after I shut down nodes A and B, I pulled up node C's web GUI. I was unable to log into node C (the GUI kept telling me that I was using an invalid pw?), so I attempted the same thing on node D, with the same behavior.

Once nodes A and B rebooted however, I was able to log into their web GUI just fine.

I'm vaguely aware of the concept of "fencing" when one sets up HA node configurations, however I do not think that I have set up any HA options in my cluster.

Is there a reason why I was unable to log into the web GUI while 2 of my nodes were offline? Is this a deliberate way to keep me from logging in and making (potentially dangerous) changes while half of the cluster was offline? Would I (likely) have been able to log in with only ONE of the nodes offline?

Thanks.
 

UdoB

Renowned Member
Nov 1, 2016
379
102
63
Germany
Hello,

when two of four nodes are unavailable the remaining nodes are no longer more than 50%. You lost quorum.

Log in via ssh and
  • look at the current state: pvecm status
  • tell the system to temporarily accept that: pvecm expected 2
Then you should be able to use the Webgui again.

Best regards
 
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itNGO

Well-Known Member
Jun 12, 2020
573
125
48
44
Germany
it-ngo.com
4-Node Cluster means at all time 3 Nodes need to be online and ready to call it a majority vote.
When 2 Nodes are down, your cluster is in a "failure" state and unpredicted behavior is expected....

So for your Cluster, 1 Node at a time is the maximum you can shutdown and maintenance without any hazzle....
 
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Reactions: loneboat

loneboat

Member
Jan 17, 2019
36
2
13
32
Hello,

when two of four nodes are unavailable the remaining nodes are no longer more than 50%. You lost quorum.

Log in via ssh and
  • look at the current state: pvecm status
  • tell the system to temporarily accept that: pvecm expected 2
Then you should be able to use the Webgui again.

Best regards
4-Node Cluster means at all time 3 Nodes need to be online and ready to call it a majority vote.
When 2 Nodes are down, your cluster is in a "failure" state and unpredicted behavior is expected....

So for your Cluster, 1 Node at a time is the maximum you can shutdown and maintenance without any hazzle....

Thanks both, this answers my question perfectly.
 

nemocx

New Member
Nov 11, 2022
1
0
1
Hello,

when two of four nodes are unavailable the remaining nodes are no longer more than 50%. You lost quorum.

Log in via ssh and
  • look at the current state: pvecm status
  • tell the system to temporarily accept that: pvecm expected 2
Then you should be able to use the Webgui again.

Best regards
Thanks for this info. I was able to login by setting pvecm expected to 1
 
Last edited:

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