MySQL Bin Files Eating Lots of Disk Space

Posted on in Categories , , , , , , , last updated December 18, 2008

Q. I get a large amount of bin files in the MySQL data directory called “server-bin.n” or mysql-bin.00000n, where n is a number that increments. What is MySQL Binary Log? How do I stop these files being created?

A. Usually /var/lib/mysql stores the binary log files. The binary log contains all statements that update data or potentially could have updated it. For example, a DELETE or UPDATE which matched no rows. Statements are stored in the form of events that describe the modifications. The binary log also contains information about how long each statement took that updated data.

The purpose of MySQL Binary Log

The binary log has two important purposes:

  • Data Recovery : It may be used for data recovery operations. After a backup file has been restored, the events in the binary log that were recorded after the backup was made are re-executed. These events bring databases up to date from the point of the backup.
  • High availability / replication : The binary log is used on master replication servers as a record of the statements to be sent to slave servers. The master server sends the events contained in its binary log to its slaves, which execute those events to make the same data changes that were made on the master.

Disable MySQL binlogging

If you are not replicating, you can disable binlogging by changing your my.ini or my.cnf file. Open your my.ini or /etc/my.cnf (/etc/mysql/my.cnf), enter:
# vi /etc/my.cnf
Find a line that reads “log_bin” and remove or comment it as follows:

#log_bin                        = /var/log/mysql/mysql-bin.log

You also need to remove or comment following lines:

#expire_logs_days        = 10
#max_binlog_size         = 100M

Close and save the file. Finally, restart mysql server:
# service mysql restart

Purge Master Logs

If you ARE replicating, then you need to periodically RESET MASTER or PURGE MASTER LOGS to clear out the old logs as those files are necessary for the proper operation of replication. Use following command to purge master logs:

$ mysql -u root -p 'MyPassword' -e "PURGE BINARY LOGS TO 'mysql-bin.03';"

OR

$ mysql -u root -p 'MyPassword' -e "PURGE BINARY LOGS BEFORE '2008-12-15 10:06:06';"

Suggested readings:

MySQL Manual – The binary logs

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

14 comment

  1. If you are using
    expire_logs_days = 10
    max_binlog_size = 100M
    You will not need to do purge logs manually .. logs older than 10 days will be purged automatically by mysql server …

    Thanks

  2. #!/bin/bash
    CURRENT_LOGFILE=$(/usr/bin/mysql -u root -p -S -e "SHOW SLAVE STATUS\G" | awk '$1 == "Master_Log_File:" {print $2}')
    echo "Purging Master Logs before ${CURRENT_LOGFILE}"
    /usr/bin/mysql -uroot -p -h -P -e "PURGE MASTER LOGS TO '${CURRENT_LOGFILE}'"
    echo "Purging Slave Logs before Current Log'"
    /usr/bin/mysql -uroot -p -h -S -e "purge binary logs before now();"
    exit $?

  3. Hi, just a small correction:
    About the High availability / replication section. It states that the Master sends the binary logs to the slave. However, it’s actually the slave that pulls the log/data from the master.

    “Each slave that connects to the master requests a copy of the binary log. That is, it pulls the data from the master, rather than the master pushing the data to the slave”
    Source: http://dev.mysql.com/doc/refman/5.0/en/replication-implementation.html

  4. Alternatively we can simply use this command

    mysql> PURGE BINARY LOGS BEFORE DATE_SUB( NOW( ), INTERVAL 7 DAY);

    It deletes all old logs older than 7 days.

Leave a Comment