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Running multiple instances

Login to your existing mysql instance and run the below statement to create a user.

GRANT SHUTDOWN ON *.* TO 'multi_admin'@'localhost' IDENTIFIED BY '*******';FLUSH PRIVILEGES;

Ifyou already have an instance ofMySQL running then youll want to shut it down before

beginning. You can do this at the command prompt with

linux-v0wq:/etc # service mysql stop

Next we need to edit the my.cnf file

First we need to comment out a few lines in the mysqld section

# The MySQL server

[mysqld]

#port = 3306

#socket = /var/lib/mysql/mysql.sock

#datadir = /var/lib/mysql/

Add the lines below and the mysqld line tells the mysqld_multi script the MySQL binary to use.

[mysqld_multi]

mysqld=/usr/bin/mysqld_safe

mysqladmin=/usr/bin/mysqladmin

log=/var/log/mysqld_multi.log

user=multi_admin

password=******

Add the below line to create 3 instances. It is critical that each instance has its own unique values or

the server will fail to start or your data could be corrupted.

[mysqld1]

server-id=1001

port=3306

datadir=/var/lib/mysql/airtel

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pid-file=/var/lib/mysql/mysqld.pid

socket=/var/lib/mysql/mysql.sock

user=mysql

log-err=/var/log/airtel.err

log-bin=airtel-bin

log-slave-updates

expire-logs-days=7

[mysqld2]

server-id=1002

port=3307

datadir=/var/lib/mysql/vodafone_212

pid-file=/var/lib/mysql/mysqld.pid2

socket=/var/lib/mysql/mysql.sock2

user=mysql

log-err=/var/log/vodafone_212.err

log-bin=vodafone_212-bin

log-slave-updates

expire-logs-days=7

[mysqld3]

server-id=1003

port=3308

datadir=/var/lib/mysql/mtnl

pid-file=/var/lib/mysql/mysqld.pid3

socket=/var/lib/mysql/mysql.sock3

user=mysql

log-err=/var/log/mtnl.err

log-bin=mtnl-bin

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log-slave-updates

expire-logs-days=7

Next create all the required directories

#mkdir airtel

#mkdir Vodafone_212

#mkdir MTNL

#/var/lib/mysql/airtelCopy the mysql database files from the original instance to the instances database directory. Then

this instance will have all of the same users as instance 1

#cp -r /var/lib/mysql/mysql airtel/#cp -r /var/lib/mysql/mysql Vodafone_212/#cp -r /var/lib/mysql/mysql MTNL/

Change the owner of the data directory to the mysql user so the instance can read them.

# chown -R mysql:mysql /var/lib/airtel

# chown -R mysql:mysql /var/lib/Vodafone_212

# chown -R mysql:mysql /var/lib/MTNL

Finally we are ready to start up the instances.

# mysqld_multi start

To check both instances have started correctly execute the below command.

# mysqld_multi report

Reporting MySQL servers

MySQL server from group: mysqld1 is running

MySQL server from group: mysqld2 is running

You can see that the mysqld_multi script has started multiple mysql processes with the following

commands

linux-v0wq:~ # ps -e | grep "mysql"

12916 ? 00:00:00 mysqld_safe

13014 ? 00:00:00 mysqld

13040 ? 00:00:00 mysqld_safe

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13138 ? 00:00:00 mysqld

13156 ? 00:00:00 mysqld_safe

13254 ? 00:00:00 mysqld

To stop both instances just execute the below command.

# mysqld_multi stop

We are also able to control individual instances by referring to the assigned number.

# mysqld_multi stop 1

# mysqld_multi report

Reporting MySQL servers

MySQL server from group: mysqld1 is not running

MySQL server from group: mysqld2 is running

# mysqld_multi start 1

# mysqld_multi reportReporting MySQL servers

MySQL server from group: mysqld1 is running

MySQL server from group: mysqld2 is running