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I have to update the os on a few servers and I need to remove a db from the cluster.

wsrep_cluster_address='gcomm://192.168.2.59,192.168.2.60,192.168.2.61,192.168.2.62,192.168.2.63' 

Do I remove the ip adress from the cluster line then restart each node? Or do I stop the service on the server I want to remove from the cluster then remove the ip address on the other nodes then restart the mysql service?

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  • What is the goal? To change from a 5-node cluster to 4-node? To simulate a crash of one node? To do some maintenance of the one node? (The answer to your question depends on the goal.)
    – Rick James
    Commented Oct 29, 2021 at 13:44
  • The goal is to upgrade from mysql 5.7 to 8 as well as upgrade my OS. I believe I will also need to upgrade galera (unsure on this). The upgraded server I will make a cluster to see if upgrade was successful. If successful I will upgrade the other servers. Commented Oct 29, 2021 at 13:56

2 Answers 2

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To work on upgrading a node, this is probably the 'right' approach: pretend that the node crashed.

  1. Stop MySQL (on the one node).
  2. Upgrade Percona-MySQL and/or OS.
  3. Restart MySQL. At this point, the one node will announce that is has 'recovered'. The 5 nodes will have a conference and decide which of the 4 will help the 1 get back in sync. Maybe via IST, probably SST.

I don't think there is any need to change the wsrep settings.

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as addition to answers above, since you will upgrade the OS and the DB, it's good if you also :

  • test it first at local VM. Preferably with full or subset of the data. Some settings and config at the OS or DB might be obselete and changed.

  • do full backup before doing anything at the production server. Always create ways to revert all actions if something going wrong.

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