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2.13.4 Recover prolonged node downtime or corrupted replication
Multi-Master replication used by IRP failover is able to cope with downtime of less than 24 hours. Replication will not be able to continue in case of prolonged downtime or corrupt replications. Recovery in this case might use either:
- new server: follow configuration steps as detailed in Initial failover configuration.
- same server: follow recovery steps below.
MySQL Multi-Master recovery prerequisites #
Before proceeding with recovery of replication the following prerequisites must be met:
- Currently active IRP node is designated as MySQL sync ‘origin’. This node currently stores reference configuration parameters and data. These will be synced to the node being recovered and we designate it as ‘destination’.
- Recovery should be scheduled during non-peak hours.
- Recovery must finish before bgpd.db.timeout.withdraw (default 4h) expires. If recovery can not be completed in time it is required to start MySQL on the active node.
MySQL Multi-Master recovery procedure #
It shall be noted that recovery closely follows actions described in Section 2.13.1 and Section 2.13.1 with the clarification that data and files from origin node target destination node (instead of IRP failover master files targeting IRP failover slave). Refer sections Section 2.13.1, Section 2.13.1 for details about the steps below.
The steps are as follows:
- destination: stop irp, mysqld
- origin: sync /etc/noction/db.* to slave:/etc/noction/
- origin: sync /root/.my.cnf to slave:/root/.my.cnf
- origin: sync /var/lib/mysql/ to slave:/var/lib/mysql/
exclude files:
master.info relay-log.info -bin.* -relay.*wait until sync at (4) succeeds and continue with: - origin: stop irp (except bgpd), mysqld
- origin: delete files master.info relay-log.info -bin.* -relay.*
- origin: sync /var/lib/mysql/ to slave:/var/lib/mysql/
- destination: start mysqld and check /var/log/mysqld.log for errors
- origin: start mysqld and check /var/log/mysqld.log for errors
- origin: run CHANGE MASTER TO from the /usr/share/doc/irp/changemasterto template
- destination: run CHANGE MASTER TO from the /usr/share/doc/irp/changemasterto template
- destination: show slave status \G
- origin: show slave status \G
- origin: start IRP (bgpd should be already running)
- destination: start IRP