title: MySQL Replication: Question about a fallback-system
body: <p>I want to set up a complete server (apache, mysql 5.7) as a fallback of a productive server.
  The synchronization on file level using rsync and cronjob is already done.</p>
  <p>The mysql-replication is currently the problem. More precisely: the choice of the right replica method.</p>
  <p>Multi primary group replication seemed to be the most suitable method so far.
  In case of a longer production downtime, it is possible to switch to the fallback server quickly via DNS change.
  Write accesses to the database are possible immediately without adjustments.</p>
  <p>So far so good: But, if the fallback-server fails, it is in unreachable status and the production-server switches to read only, since its group no longer has the quota. This is of course a no-go.
  I thought it might be possible using different replica variables: If the fallback-server is in unreachable state for a certain time (~5 minutes), the production-server should stop the group_replication and start a new group_replication. This has to happen automatically to keep the read-only time relatively low. When the fallback-server is back online, it should be manually added to the newly started group. But if I read the various forum posts and documentation correctly, it's not possible that way. And running a Group_Replication with only two nodes is the wrong decision anyway.</p>
  <p><a href="https://forums.mysql.com/read.php?177,657333,657343#msg-657343" rel="nofollow noreferrer">https://forums.mysql.com/read.php?177,657333,657343#msg-657343</a></p>
  <p>Is the master - slave replication the only one that can be considered for such a fallback system? <a href="https://dev.mysql.com/doc/refman/5.7/en/replication-solutions-switch.html" rel="nofollow noreferrer">https://dev.mysql.com/doc/refman/5.7/en/replication-solutions-switch.html</a></p>
  <p>Or does the Group_Replication offer possibilities after all, if you can react suitably to the quota problem? Possibilities that I have overlooked so far.</p>
  <p>Many thanks and best regards</p>