Working with Binary Logs¶
The xtrabackup binary integrates with information that InnoDB stores in
its transaction log about the corresponding binary log position for committed
transactions. This enables it to print out the binary log position to which a
backup corresponds, so you can use it to set up new replication replicas or
perform point-in-time recovery.
Finding the Binary Log Position¶
You can find the binary log position corresponding to a backup once the backup
has been prepared. This can be done by either running xtrabackup --prepare or innobackupex --apply-log. If your backup is from a
server with binary logging enabled, xtrabackup will create a file named
xtrabackup_binlog_info in the target directory. This file contains the
binary log file name and position of the exact point in the binary log to which
the prepared backup corresponds.
You will also see output similar to the following during the prepare stage:
InnoDB: Last MySQL binlog file position 0 3252710, file name ./mysql-bin.000001
... snip ...
[notice (again)]
If you use binary log and don't use any hack of group commit,
the binary log position seems to be:
InnoDB: Last MySQL binlog file position 0 3252710, file name ./mysql-bin.000001
This output can also be found in the xtrabackup_binlog_pos_innodb file,
but it is only correct when no other than XtraDB or InnoDB are used as
storage engines.
If other storage engines are used (i.e. MyISAM), you should use the
xtrabackup_binlog_info file to retrieve the position.
The message about hacking group commit refers to an early implementation of emulated group commit in Percona Server for MySQL.
Point-In-Time Recovery¶
To perform a point-in-time recovery from an xtrabackup backup, you should
prepare and restore the backup, and then replay binary logs from the point shown
in the xtrabackup_binlog_info file.
A more detailed procedure is found here (with innobackupex).
Setting Up a New Replication Replica¶
To set up a new replica, you should prepare the backup, and restore it to the
data directory of your new replication replica. Then in your CHANGE MASTER TO
command, use the binary log filename and position shown in the
xtrabackup_binlog_info file to start replication.
A more detailed procedure is found in How to setup a replica for replication in 6 simple steps with Percona XtraBackup.