Remove node from percona xtradb cluster



  • I have a 5 node cluster. When I run backups it locks the entire cluster. I use DDL statements in a stored procedure that is used heavily. What I am trying to achieve is taking one node out of the cluster. Running the backup then adding the node back to the cluster.
    How do I remove a node from a cluster?

     set wsrep_cluster_address = gcomm://192.168.2.59,192.168.2.60,192.168.2.61,192.168.2.62
    

    Leaving the the node I want to backup out of the update. On the node I want to backup do I set wsrep_cluster_address:

     set wsrep_cluster_address = gcomm://
    

    Do I change the cluster name on the node as well?



  • I wouldn't remove the node, it's sufficient to desync it from the cluster:

    SET GLOBAL wsrep_desync=ON;
    

    Then do the backup. Then:

    SET GLOBAL wsrep_desync=OFF;
    

    When a node is desynced, it will remain part of the cluster. The node will receive transactions, but not process them. Flow control is disabled, which allows the node to fall behind the cluster. Once we turn off desync again, it will process the queued up transactions.

    During desync, the status variable wsrep_cluster_size doesn't change, and the node itself will have wsrep_connected=ON, wsrep_ready=ON as before. However, it will also have wsrep_local_state_comment='Donor/Desynced'.

    For your DDL statements, I think your options are:

    • pt-online-schema-change
    • wsrep_OSU_method = RSU
    • wsrep_OSU_method = https://www.percona.com/blog/percona-xtradb-cluster-non-blocking-operation-for-online-schema-upgrade/



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