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gijs007
Asked: 2015-07-08 17:40:52 +0800 CST

Galera cluster implementation questions

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I've just successfully created my first Galera cluster using MariaDB 10.0.20 between three servers.

I have a few questions regarding my implementation: 1. what will happen if one server becomes isolated from the other servers but still has clients connected? 2. What happens if two servers can't directly communicate but the third server can talk with both servers? 3. Is it possible to upgrade one server at a time? 4. Is it possible to make configuration changes to one server at a time (e.g enabling query cache)

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1 Answers

  1. Best Answer
    1. what will happen if one server becomes isolated from the other servers but still has clients connected?

    The isolated server becomes not read or writeable and will when the isolation ends get itself back in sync using one of the other nodes.

    1. What happens if two servers can't directly communicate but the third server can talk with both servers?

    Its likely that those two servers will isolate themselves (non-primary mode).

    1. Is it possible to upgrade one server at a time?

    yes. Wait until one is in sync before moving to the next.

    1. Is it possible to make configuration changes to one server at a time (e.g enabling query cache)

    Yes. Be careful about changing some of the setting related to galera as these may create a writeset that the other nodes can't understand.

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