MySQL: Backup strategy - Master or Slave?

Question

We have a set up of MySQL (version 5.1) with Master-Slave setup. We need to propose a backup strategy and we are going to use mysqldump .

We intend to use flushlogs , master-date=2 and single-transaction options.

I just want to know from which node its better to run the backup from, Master or Slave?

Answer 1

You should be running your backups on the Slave so that the Master is not interrupted in any way and the Master can stay in Production mode.

Here is a script to backup mysql data on the Slave and keep only the last 7 backups

MYSQL_USER=root
MYSQL_PASS=rootpass
MYSQL_CONN="-u${MYSQL_USER} -p${MYSQL_PASS}"
BACKUP_HOME=/some/path/to/your/backups
BACKUP_TIME=`date +"%Y%m%d_%H%M%S"`
BACKUP_FILE=${BACKUP_HOME}/MySQLData_${BACKUP_TIME}.sql
BACKUP_GZIP=${BACKUP_FILE}.gz

MYSQLDUMP_OPTIONS="--single--transaction --routines --triggers"
#
# Stop Replication
# Dump the Data
# Resume Replication
#
mysql ${MYSQL_CONN} -ANe"STOP SLAVE"
mysqldump ${MYSQL_CONN} ${MYSQLDUMP_OPTIONS} -A | gzip > ${BACKUP_GZIP}
mysql ${MYSQL_CONN} -ANe"START SLAVE"

#
# Rotate Out Old Backups based on BACKUPS_TO_KEEP
#
cd ${BACKUP_HOME}
FILES_TO_DELETE=/tmp/BackupFilesToDelete.txt
BACKUPS_TO_KEEP=7
BACKUPS_ON_HAND=`ls MySQLData_*.gz | wc -l`
if [ ${BACKUPS_ON_HAND} -gt ${BACKUPS_TO_KEEP} ]
then
    (( DIFF = BACKUPS_ON_HAND - BACKUPS_TO_KEEP ))
    ls -l MySQLData_*.gz | head -${DIFF} > ${FILES_TO_DELETE}
    for FIL in `cat ${FILES_TO_DELETE}` ; do rm -f ${FIL} ; done
fi

You cannot use --master-data=2 because the backup is from the Slave and not the Master. If you upgrade MySQL 5.5, you could use --dump-slave in the MYSQLDUMP_OPTIONS to capture the Master's binary log and position from the SHOW SLAVE STATUS\\G . You will find the output of --dump-slave on line 23 of the dump.

If you wish to remain with MySQL 5.1 and you want to record the coordinates from the Master, use this

MYSQL_USER=root
MYSQL_PASS=rootpass
MYSQL_CONN="-u${MYSQL_USER} -p${MYSQL_PASS}"
BACKUP_HOME=/some/path/to/your/backups
BACKUP_TIME=`date +"%Y%m%d_%H%M%S"`
BACKUP_COOR=${BACKUP_HOME}/MySQLCoor_${BACKUP_TIME}.txt
BACKUP_FILE=${BACKUP_HOME}/MySQLData_${BACKUP_TIME}.sql
BACKUP_GZIP=${BACKUP_FILE}.gz

MYSQLDUMP_OPTIONS="--single--transaction --routines --triggers"
#
# Stop Replication
# Dump the Data
# Capture Master Coordinates
# Resume Replication
#
mysql ${MYSQL_CONN} -ANe"STOP SLAVE"
mysqldump ${MYSQL_CONN} ${MYSQLDUMP_OPTIONS} -A | gzip > ${BACKUP_GZIP}
mysql ${MYSQL_CONN} -Ae"SHOW SLAVE STATUS\G" > /tmp/SSS.txt
grep "Relay_Master_Log_File:" /tmp/SSS.txt  > ${BACKUP_COOR}
grep "Exec_Master_Log_Pos:"   /tmp/SSS.txt >> ${BACKUP_COOR}
mysql ${MYSQL_CONN} -ANe"START SLAVE"
#
# Rotate Out Old Backups based on BACKUPS_TO_KEEP
#
cd ${BACKUP_HOME}
FILES_TO_DELETE=/tmp/BackupFilesToDelete.txt
BACKUPS_TO_KEEP=7
BACKUPS_ON_HAND=`ls MySQLData_*.gz | wc -l`
if [ ${BACKUPS_ON_HAND} -gt ${BACKUPS_TO_KEEP} ]
then
    (( DIFF = BACKUPS_ON_HAND - BACKUPS_TO_KEEP ))
    ls -l MySQLData_*.gz | head -${DIFF} > ${FILES_TO_DELETE}
    for FIL in `cat ${FILES_TO_DELETE}` ; do rm -f ${FIL} ; done
fi

If you want to autorotate binary logs on the Master, just configure this on the Master

[mysqld]
expire-logs-days=7

Give it a Try !!!

Answer 2

Following is how I tackled this problem many moons ago:

#!/usr/bin/ksh
date=`date +%y%m%d`
mysql -u root db_name -e "flush tables with read lock;"
mysqldump -u root -pYrPass --add-drop-table --add-locks natl_inv > /path/to/backup/db_name$date
mysql -u root -e "reset master;"
mysql -u root db_name -e "unlock tables;"
mysql -u root –pYrPass db_name < /path/to/backup/db_name$date
mysql -u root -e "flush logs;"

On the slave(s): use show slave status command to verify you are in sync with the master. If you want to resync to the master, run:

slave stop;
reset slave;
slave start;

You may need to stop mysql, delete the slave bin log files then restart and run the above (this was important for us because we had a rogue app upsetting mysql configurations on the slaves).

This strategy served our purposes extremely well. Be sure and test out to make sure it fits your needs.