Backing Up Raw Data from a Slave
To guarantee the integrity of the files that are copied, backing up the raw data files on your MySQL
replication slave should take place while your slave server is shut down. If the MySQL server is still
running, background tasks may still be updating the database files, particularly those involving storage
engines with background processes such as InnoDB. With InnoDB, these problems should be
resolved during crash recovery, but since the slave server can be shut down during the backup process
without affecting the execution of the master it makes sense to take advantage of this capability.
To shut down the server and back up the files:
1. Shut down the slave MySQL server:
shell mysqladmin shutdown
2. Copy the data files. You can use any suitable copying or archive utility, including cp, tar or
WinZip. For example, assuming that the data directory is located under the current directory, you
can archive the entire directory as follows:
shell tar cf /tmp/dbbackup.tar ./data
3. Start the MySQL server again. Under Unix:
shell mysqld_safe &
C:\ "C:\Program Files\MySQL\MySQL Server 5.6\bin\mysqld"
Normally you should back up the entire data directory for the slave MySQL server. If you want to be
able to restore the data and operate as a slave (for example, in the event of failure of the slave), then in
addition to the slave's data, you should also back up the slave status files, the master info and relay log
info repositories, and the relay log files. These files are needed to resume replication after you restore
the slave's data.
If you lose the relay logs but still have the relay-log.info file, you can check it to determine how far
the SQL thread has executed in the master binary logs. Then you can use CHANGE MASTER TO with
the MASTER_LOG_FILE and MASTER_LOG_POS options to tell the slave to re-read the binary logs from
that point. This requires that the binary logs still exist on the master server.
If your slave is replicating LOAD DATA INFILE statements, you should also back up any SQL_LOAD-
* files that exist in the directory that the slave uses for this purpose. The slave needs these files to
resume replication of any interrupted LOAD DATA INFILE operations. The location of this directory is
the value of the --slave-load-tmpdir  option. If the server was not started with that option,
the directory location is the value of the tmpdir  system variable.
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