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  1. RHEL
  2. RHEL-7700

Improve error message when adding a new node to a cluster with sbd is not possible

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    • rhel-9.4
    • rhel-9.2.0
    • pcs
    • pcs-0.11.6-6.el9
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    • sst_high_availability
    • ssg_filesystems_storage_and_HA
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      Feature:
      Provide a guidance in error messages when adding or removing a node in a cluster with odd number of nodes, SBD enabled without disks, and auto_tie_breaker disabled.

      Reason:
      Originally, pcs in this situation just informed, that it was going to enable auto_tie_breaker, and then exited with an error saying corosync was running. This was not explanatory and it didn't provide enough information for users to solve this issue.

      Result:
      Error messages have been updated. They now explain that auto_tie_breaker must be enabled due to SBD and provide instructions to stop the cluster, enable auto_tie_breaker, start the cluster and run command for adding or removing a node again.
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      Feature: Provide a guidance in error messages when adding or removing a node in a cluster with odd number of nodes, SBD enabled without disks, and auto_tie_breaker disabled. Reason: Originally, pcs in this situation just informed, that it was going to enable auto_tie_breaker, and then exited with an error saying corosync was running. This was not explanatory and it didn't provide enough information for users to solve this issue. Result: Error messages have been updated. They now explain that auto_tie_breaker must be enabled due to SBD and provide instructions to stop the cluster, enable auto_tie_breaker, start the cluster and run command for adding or removing a node again.
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      Description of problem:
      pcs can get to a situation, when adding a new node to a cluster with sbd is impossible, because there are 2 conditions - one prompting the user that cluster has to be offline due to auto_tie_breaker and the other one that it is not possible to get CIB (because the cluster is offline). Pcs should be aware of this situation and provide a more intuitive output.

      Version-Release number of selected component (if applicable):
      found in pcs-0.11.4-6.el9

      How reproducible:
      every time the number of nodes would be even after adding a node (thus the cluster would have auto_tie_breaker) and sbd without disks is used.

      Steps to Reproduce:

        1. enable sbd on 3 node cluster

      [root@virt-553 ~]# pcs stonith sbd enable
      Running SBD pre-enabling checks...
      virt-484: SBD pre-enabling checks done
      virt-493: SBD pre-enabling checks done
      virt-553: SBD pre-enabling checks done
      Distributing SBD config...
      virt-553: SBD config saved
      virt-493: SBD config saved
      virt-484: SBD config saved
      Enabling sbd...
      virt-493: sbd enabled
      virt-484: sbd enabled
      virt-553: sbd enabled
      Warning: Cluster restart is required in order to apply these changes.

      [root@virt-553 ~]# pcs cluster stop --all && pcs cluster start --all
      virt-553: Stopping Cluster (pacemaker)...
      virt-484: Stopping Cluster (pacemaker)...
      virt-493: Stopping Cluster (pacemaker)...
      virt-493: Stopping Cluster (corosync)...
      virt-553: Stopping Cluster (corosync)...
      virt-484: Stopping Cluster (corosync)...
      virt-553: Starting Cluster...
      virt-493: Starting Cluster...
      virt-484: Starting Cluster...

        1. Try to add new node to the cluster

      1. in a running cluster

      [root@virt-553 ~]# pcs cluster node add virt-551
      No addresses specified for host 'virt-551', using 'virt-551'
      No watchdog has been specified for node 'virt-551'. Using default watchdog '/dev/watchdog'
      Warning: auto_tie_breaker quorum option will be enabled to make SBD fencing effective. Cluster has to be offline to be able to make this change.
      Checking corosync is not running on nodes...
      Error: virt-493: corosync is running
      Error: virt-484: corosync is running
      Error: virt-553: corosync is running
      Running SBD pre-enabling checks...
      virt-551: SBD pre-enabling checks done
      Error: Errors have occurred, therefore pcs is unable to continue
      [root@virt-553 ~]# echo $?
      1

      > Node can't be added in a running cluster due to auto_tie_breaker sbd check.

      2. in a stopped cluster

      [root@virt-553 ~]# pcs cluster stop --all
      virt-553: Stopping Cluster (pacemaker)...
      virt-493: Stopping Cluster (pacemaker)...
      virt-484: Stopping Cluster (pacemaker)...
      virt-484: Stopping Cluster (corosync)...
      virt-553: Stopping Cluster (corosync)...
      virt-493: Stopping Cluster (corosync)...

      [root@virt-553 ~]# pcs cluster node add virt-551
      No addresses specified for host 'virt-551', using 'virt-551'
      No watchdog has been specified for node 'virt-551'. Using default watchdog '/dev/watchdog'
      Error: Unable to load CIB to get guest and remote nodes from it, those nodes cannot be considered in configuration validation, use --force to override
      Warning: auto_tie_breaker quorum option will be enabled to make SBD fencing effective. Cluster has to be offline to be able to make this change.
      Checking corosync is not running on nodes...
      virt-484: corosync is not running
      virt-553: corosync is not running
      virt-493: corosync is not running
      Running SBD pre-enabling checks...
      virt-551: SBD pre-enabling checks done
      Error: Errors have occurred, therefore pcs is unable to continue
      [root@virt-553 ~]# echo $?
      1

      > Node can't be added in a stopped cluster because CIB is unavailable.

      Actual results:
      In this state, it's not possible to add a node (without using --force), because the 2 checks are mutually exclusive - cluster needs to be stopped for auto_tie_breaker and cluster needs to be started to get CIB.

      Expected results:
      More intuitive error message, which explains the situation why the node in this state can never be added and what to do to solve it (for example disable sbd first). Alternative solutions can be discussed as well.

            cluster-qe Cluster QE
            mmazoure Michal Mazourek
            Tomas Jelinek Tomas Jelinek
            Nina Hostakova Nina Hostakova
            Steven Levine Steven Levine
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              Created:
              Updated:
              Resolved: