Change Replication Master: node missing from pull-down ...
I cannot change the replication master in the dashboard via [NodeActions->ChangeReplicationMaster]; the slave node is not in the [Select a Node] pull-down. The same when selecting the multi-master node that is in read-only mode.
I believe GTID replication is active; both nodes have Executed GTIDs. However, only the multi-master in read-only has a Retrieved GTID. Might this be the issue, or can't this action be performed in the community-version?
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Hi,
For MySQL multi-master replication, the "master" in the dropdown list is the one that produces binary log and read_only = OFF. An existing master cannot be demoted to a slave, unless you promote a slave (the read-only master) to become a new master, by explicitly pick the read-only node -> Promote Slave.
After a new master is promoted, you can the change the old master to become a slave by using "Rebuild Replication Slave" and pick the new master from the dropdown list.
Regards,
Ashraf -
Thank you for the explanation. Neuco only has the community version and promoting a read-only master cannot be done as this capability is "... not available in the Community Edition." A few questions:
- Must I manually (from the CLI) promote the read-only master to become the new read-write master? And, then, if I must do this manually, will I be able to re-build the new read-only master via the dashboard's "Rebuild Replication Slave"?
- If I do not have to manually promote read-only masters, then what may be the issue when trying to promote a read-only master to the new read-write master?
Lastly, would you kindly point out where does, in the documentation, this procedure exists, or for that matter any of the procedures, to promote and demote master and slave databases that are configured for basic MySQL master-master (or master-slave) replication.
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Hi,
Unfortunately, ClusterControl does not provide free management features including topology changes (failover to new master, rebuild replication slave, promote slave etc.). This includes s9s CLI, which respects the license of the controller server.
You probably need to perform those procedures manually. We have several resources related to this:
- https://severalnines.com/blog/new-whitepaper-mysql-replication-blueprint#no
- https://severalnines.com/blog/become-mysql-dba-blog-series-common-operations-replication-topology-changes
- https://severalnines.com/blog/mysql-replication-and-gtid-based-failover-deep-dive-errant-transactionsRegards,
Ashraf
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