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How do I check my Galera sync status?
I know to check the Galera cluster status, the command that should be used after login to the mysql client is: SHOW STATUS LIKE ‘wsrep%’;
What is Galera cache?
Percona XtraDB Cluster is a multi-master topology, where a transaction executed on one node is replicated on another node(s) of the cluster. This transaction is then copied over from the group channel to Galera-Cache followed by apply action. So in short, GCache acts as a temporary storage for replicated transactions.
What is PT-table-checksum?
pt-table-checksum performs an online replication consistency check by executing checksum queries on the master, which produces different results on replicas that are inconsistent with the master. The optional DSN specifies the master host. If any data is different, you can resolve the problem with pt-table-sync.
How to check if MySQL is synced with Galera?
Slave_IO_Running: Yes Slave_SQL_Running: Yes Seconds_Behind_Master: 0 The seconds_behind_master always let me know if I was behind on one of my servers. I am not using galera and am not sure how to verify if everything is up to date. I have come across this article “Monitoring Cluster Status”
How to recover an out of sync MariaDB Galera database cluster?
For example when someone without thinking reboots all nodes in a cluster without shutting down the databases first. Place all cluster hosts into standby mode and cleanup any failed resources. I sugguest making a back-up of Mariadb on each controller nodes – just in case.
How to check the status of a Galera Cluster?
Galera Cluster variables are related to write-set replication and thereby prefixed with wsrep_. To retrieve a list of all of these status variables, you would enter the following SQL statement on each node, using a simple database client, such as mysql:
What happens if all nodes fail in Galera?
In this scenario, all nodes except one fail which causes loss of quorum. At this stage, Galera cluster can no longer process SQL requests. Since one node is still up and running, no data is lost. If failed nodes do come back online they cannot rejoin the cluster, because the cluster does not exist.