Architecture:
MySQL 5.6.24 two node active-passive cluster managed by Pacemaker (with MySQL replication), with DRDB mirrored file system for the Magento application tier.
What we need to do:
Rolling upgrade to 5.6.29, with no interruption to service and no data loss.
High Level Plan: [LIST=1]
[]Put Pacemaker in maintenance mode
[]Shutdown the slave database (database B).
[]Upgrade the MySQL binary packages for database B.
[]Start database B.
[]Run the upgrade script
[]Restart MySQL replication and let the Slave (B) resync with the master (A). Check DRBD is up to date.
[]Promote B to Master.
[]Shutdown the old master database (A)
[]Upgrade the MySQL binary packages for database A
[]Start database A.
[]Run the upgrade script
[]Restart MySQL replication and let it sync with database B. Check DRBD is up to date
[]Promote A to master
[]Turn Pacemaker maintenance mode off.
[*]Ensure Slave (B) resyncs with the master (A).
[/LIST]