How to create a new (or repair a broken) GTID-based replica¶
MySQL 5.6 introduced the Global Transaction
support in replication. Percona XtraBackup automatically
GTID value in the
xtrabackup_binlog_info when doing the
backup of MySQL and Percona Server for MySQL 5.7 with the
information can be used to create a new (or repair a broken)
1. Take a backup from any server on the replication environment, source or replica¶
The following command takes a backup and saves it in
$ xtrabackup --backup --target-dirs=/data/backups/
In the destination folder, there will be a file with the name
xtrabackup_binlog_info. This file contains both binary log coordinates
$ cat xtrabackup_binlog_info
mysql-bin.000002 1232 c777888a-b6df-11e2-a604-080027635ef5:1-4
That information is also printed by xtrabackup after taking the backup:
xtrabackup: MySQL binlog position: filename 'mysql-bin.000002', position 1232, GTID of the last change 'c777888a-b6df-11e2-a604-080027635ef5:1-4'
2. Prepare the backup¶
The backup will be prepared with the following command on the Source:
$ xtrabackup --prepare --target-dir=/data/backup
You need to select the path where your snapshot has been taken, for example
/data/backups/2013-05-07_08-33-33. If everything is ok you should get the
same OK message. Now, the transaction logs are applied to the data files,
ones are created: your data files are ready to be used by the MySQL server.
3. Move the backup to the destination server¶
Use rsync or scp to copy the data to the destination server. If you are synchronizing the data directly to the already running replica’s data directory it is advised to stop the MySQL server there.
$ rsync -avprP -e ssh /path/to/backupdir/$TIMESTAMP NewSlave:/path/to/mysql/
After you copy the data over, make sure MySQL has proper permissions to access them.
$ chown mysql:mysql /path/to/mysql/datadir
4. Configure and start replication¶
gtid_purged variable to the
xtrabackup_binlog_info. Then, update the information about the
source node and, finally, start the replica. Run the following commands on
the replica if you are using a version before 8.0.22:
# Using the mysql shell > SET SESSION wsrep_on = 0; > RESET MASTER; > SET SESSION wsrep_on = 1; > SET GLOBAL gtid_purged='<gtid_string_found_in_xtrabackup_binlog_info>'; > CHANGE MASTER TO MASTER_HOST="$masterip", MASTER_USER="repl", MASTER_PASSWORD="$slavepass", MASTER_AUTO_POSITION = 1; > START SLAVE;
If you are using version 8.0.22 or later, use
START REPLICA instead
START SLAVE is deprecated as of that release. If you
are using version 8.0.21 or earlier, use
If you are using a version 8.0.23 or later, run the following commands:
# Using the mysql shell > SET SESSION wsrep_on = 0; > RESET MASTER; > SET SESSION wsrep_on = 1; > SET GLOBAL gtid_purged='<gtid_string_found_in_xtrabackup_binlog_info>'; > CHANGE REPLICATION SOURCE TO SOURCE_HOST="$masterip", SOURCE_USER="repl", SOURCE_PASSWORD="$slavepass", SOURCE_AUTO_POSITION = 1; > START REPLICA;
If you are using version 8.0.23 or later,
use CHANGE_REPLICATION_SOURCE_TO and the appropriate options.
CHANGE_MASTER_TO is deprecated as of that release.
The example above is applicable to Percona XtraDB Cluster.
wsrep_on variable is set to 0 before resetting the source (
RESET MASTER). The reason is that Percona XtraDB Cluster will not allow resetting the source if
5. Check the replication status¶
The following command returns the replica status:
mysql> SHOW REPLICA STATUS\G
[..] Slave_IO_Running: Yes Slave_SQL_Running: Yes [...] Retrieved_Gtid_Set: c777888a-b6df-11e2-a604-080027635ef5:5 Executed_Gtid_Set: c777888a-b6df-11e2-a604-080027635ef5:1-5
We can see that the replica has retrieved a new transaction with number 5, so transactions from 1 to 5 are already on this slave.
We have created a new replica in our
GTID based replication