MySQL Database Backup – Best Practices and Tools

If you are dumping a mysql database that has a mixture of InnoDB and MyISAM and you have scheduled downtime:

mysqldump -u... -p... --master-data=1 --single-transaction --flush-privileges --routines --triggers --all-databases > /root/mydata.sql

Since --opt is enabled by default, the following options are already enabled

• --add-drop-table
• --add-locks
• --create-options
• --quick
• --lock-tables
• --set-charset
• --disable-keys

If you are concerned about InnoDB/MyISAM together in the mysqldump and you want the database placed in a read-only state, try putting a read lock across all tables manually.

MYSQL_CONN="-hhostip -uusername -ppassword"
mysql ${MYSQL_CONN} -A -e"FLUSH TABLES WITH READ LOCK; SELECT SLEEP(86400)" &
SEARCHING_FOR_SLEEP=0
while [ ${SEARCHING_FOR_SLEEP} -eq 0 ]
do
    sleep 3
    SEARCHING_FOR_SLEEP=`${MYSQL} ${MYSQL_CONN} -A -e"SHOW PROCESSLIST;" | grep -c "SELECT SLEEP(86400)"`
done
sleep 1
SLEEP_ID=`mysql ${MYSQL_CONN} -A -e"SHOW PROCESSLIST;" | grep "SELECT SLEEP(86400)" | awk '{print $1}'`

mysqldump ${MYSQL_CONN} --master-data=2 --single-transaction --flush-privileges --routines --triggers --all-databases > /root/mydata.sql

mysql ${MYSQL_CONN} -A -e"KILL ${SLEEP_ID}"

The reason this is better to do is that --single-transaction does not protect MyISAM from changing during the dump.

Before launching the mysqldump, make sure binary logging is enabled on the master. If it is not, do the following:

Step 01) Add this to /etc/my.cnf on the master

[mysqld]
log-bin=mysql-bin

Step 02) service mysql restart

This will enable binary logging on the master.

On the new slave, you can run the following command:

CHANGE MASTER TO
MASTER_HOST='IP of the master',
MASTER_PORT=3306,
MASTER_USER='whatever_username',
MASTER_PASSWORD='whatever_password',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=107;

Make sure the rep_username exists in the master. If it does not, run this command on the master:

GRANT SELECT, REPLICATION SLAVE, REPLICATION CLIENT
ON *.* TO 'whatever_username'@'%' IDENTIFIED BY 'whatever_password';

Then do the mysqldump to /root/mydata.sql.

Move the /root/mydata.sql from the master to the slave.

Next, execute in the mysql client this command on the slave:

source /root/mydata.sql

This will load mysqldump in the slave and the set the correct log file and log position in /var/lib/mysql/master.info.

Finally, run START SLAVE; on the slave and mysql replication should get going.

Run SHOW SLAVE STATUS\G to check replication status.

Give it a Try !!!

If all your database use InnoDB only, I have some good news.

You should be to dump all the database in parallel from a slave.

In fact, you can force all the databases into the same point-in-time.

First thing to remember about a the Slave is that it is not not required to have binary logging enabled if it is not a Master for other Slaves.

You cannot use --master-data option for parallel dumps because each dump will have a different position written at line 22 of each dump file. It is better to record the Master's last log file and position the Slave executed using SHOW SLAVE STATUS\G. That way, all the databases have the same point-in-time position.

You can collect all databases and script the parallel dump of all the database.

DBLIST=/tmp/ListOfDatabasesToParallelDump.txt
BACKUP_BASE=/backups
BACKUP_DATE=`date +"%Y%m%d_%H%M%S"`
BACKUP_HOME=${BACKUP_BASE}/${BACKUP_DATE}
mkdir ${BACKUP_HOME}
cd ${BACKUP_HOME}

mysql -h... -u... -p... -e"STOP SLAVE;"
mysql -h... -u... -p... -e"SHOW SLAVE STATUS\G" > ${SSS}
LOGFIL=`cat ${SSS} | grep "Relay_Master_Log_File" | awk '{print $2}'`
LOGPOS=`cat ${SSS} | grep "Exec_Master_Log_Pos"   | awk '{print $2}'`
echo "Master was at ${LOGFIL} Position ${LOGPOS} for this Backup" > Master_Log_FilePos.txt

mysql -h... -u... -p... -AN -e"SELECT schema_name FROM information_schema.schemata WHERE schema_name NOT IN ('information_schema','mysql','performance_schema')" > ${DBLIST}

for DB in `cat ${DBLIST}` 
do 
    mysqldump -h... -u... -p... --hex-blob --routines --triggers ${DB} | gzip > ${DB}.sql.gz & 
done 
wait 

mysql -h... -u... -p... -e"START SLAVE;"

If there are simply too many databases, dump them 10 or 20 at a time as follows:

DBLIST=/tmp/ListOfDatabasesToParallelDump.txt
SSS=/tmp/ShowSlaveStatusDisplay.txt
BACKUP_BASE=/backups
BACKUP_DATE=`date +"%Y%m%d_%H%M%S"`
BACKUP_HOME=${BACKUP_BASE}/${BACKUP_DATE}
mkdir ${BACKUP_HOME}
cd ${BACKUP_HOME}

mysql -h... -u... -p... -e"STOP SLAVE;"
mysql -h... -u... -p... -e"SHOW SLAVE STATUS\G" > ${SSS}
LOGFIL=`cat ${SSS} | grep "Relay_Master_Log_File" | awk '{print $2}'`
LOGPOS=`cat ${SSS} | grep "Exec_Master_Log_Pos"   | awk '{print $2}'`
echo "Master was at ${LOGFIL} Position ${LOGPOS} for this Backup" > Master_Log_FilePos.txt

mysql -h... -u... -p... -AN -e"SELECT schema_name FROM information_schema.schemata WHERE schema_name NOT IN ('information_schema','mysql','performance_schema')" > ${DBLIST}

COMMIT_LIMIT=20
COMMIT_COUNT=0    
for DB in `cat ${DBLIST}` 
do 
    mysqldump -h... -u... -p... --hex-blob --routines --triggers ${DB} | gzip > ${DB}.sql.gz & 
    (( COMMIT_COUNT++ ))
    if [ ${COMMIT_COUNT} -eq ${COMMIT_LIMIT} ]
    then
        COMMIT_COUNT=0
        wait
    fi
done 
wait 
if [ ${COMMIT_COUNT} -gt 0 ]
then
    wait
fi

mysql -h... -u... -p... -e"START SLAVE;"

If you need to recover a single table, you can parallel dump tables 20 at a time in size order.

Try this:

TBLIST=/tmp/ListOfTablesToParallelDump.txt
SSS=/tmp/ShowSlaveStatusDisplay.txt
BACKUP_BASE=/backups
BACKUP_DATE=`date +"%Y%m%d_%H%M%S"`
BACKUP_HOME=${BACKUP_BASE}/${BACKUP_DATE}
mkdir ${BACKUP_HOME}
cd ${BACKUP_HOME}

mysql -h... -u... -p... -e"STOP SLAVE;"
mysql -h... -u... -p... -e"SHOW SLAVE STATUS\G" > ${SSS}
LOGFIL=`cat ${SSS} | grep "Relay_Master_Log_File" | awk '{print $2}'`
LOGPOS=`cat ${SSS} | grep "Exec_Master_Log_Pos"   | awk '{print $2}'`
echo "Master was at ${LOGFIL} Position ${LOGPOS} for this Backup" > Master_Log_FilePos.txt

mysql -h... -u... -p... -AN -e"SELECT CONCAT(table_schema,'.',table_name) FROM information_schema.tables WHERE table_schema NOT IN ('information_schema','mysql','performance_schema') ORDER BY data_length" > ${DBLIST}

COMMIT_LIMIT=20
COMMIT_COUNT=0    
for DBTB in `cat ${TBLIST}` 
do
    DB=`echo "${DBTB}" | sed 's/\./ /g' | awk '{print $1}'`
    TB=`echo "${DBTB}" | sed 's/\./ /g' | awk '{print $2}'`
    DUMPFILE=$DB-{DB}-TBL-${TB}.sql.gz
    mysqldump -h... -u... -p... --hex-blob --routines --triggers ${DB} ${TB} | gzip >  ${DUMPFILE} & 
    (( COMMIT_COUNT++ ))
    if [ ${COMMIT_COUNT} -eq ${COMMIT_LIMIT} ]
    then
        COMMIT_COUNT=0
        wait
    fi
done 
wait 
if [ ${COMMIT_COUNT} -gt 0 ]
then
    wait
fi

mysql -h... -u... -p... -e"START SLAVE;"

Now that you have scripts to dump databases or individual tables, you can load that data at your discretion. If you need to get SQL executed from the binary logs on the master, you can use mysqlbinlog and give it the position ot datetime and output the SQL to other text files. You just have to perform due diligence to find the amount of data you need from whatever timestamps the bnary logs have. Just remember that every binary log's timestamp in the OS represents that last time it was written.