vi /etc/mysql/my.cnf

and add or change the lines for mysql max_connections and max_user_connections in the [mysqld] section of the my.cnf file:

[mysqld]
……
max_connections = 500
max_user_connections = 500
…….

Login to your server on the shell, then execute the following commands:

Download the mysqltuner script:

cd /usr/local/bin
wget http://mysqltuner.pl/mysqltuner.pl
chmod +x mysqltuner.pl

Run mysqltuner

/usr/local/bin/mysqltuner.pl

Then enter root as username and the mysql root password.

You will get a output similar to this:

root@v221:/usr/local/bin# /usr/local/bin/mysqltuner.pl

>>  MySQLTuner 1.0.1 – Major Hayden <major@mhtx.net>
>>  Bug reports, feature requests, and downloads at http://mysqltuner.com/
>>  Run with ‘–help’ for additional options and output filtering
Please enter your MySQL administrative login: root
Please enter your MySQL administrative password:

——– General Statistics ————————————————–
[--] Skipped version check for MySQLTuner script
[OK] Currently running supported MySQL version 5.0.51a-24+lenny2
[!!] Switch to 64-bit OS – MySQL cannot currently use all of your RAM

——– Storage Engine Statistics ——————————————-
[--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster
[--] Data in MyISAM tables: 26M (Tables: 215)
[!!] InnoDB is enabled but isn’t being used
[!!] Total fragmented tables: 33

——– Performance Metrics ————————————————-
[--] Up for: 96d 23h 3m 41s (10M q [1.239 qps], 686K conn, TX: 701M, RX: 1B)
[--] Reads / Writes: 44% / 56%
[--] Total buffers: 58.0M global + 2.6M per thread (100 max threads)
[OK] Maximum possible memory usage: 320.5M (12% of installed RAM)
[OK] Slow queries: 0% (20/10M)
[OK] Highest usage of available connections: 33% (33/100)
[OK] Key buffer size / total MyISAM indexes: 16.0M/8.5M
[OK] Key buffer hit rate: 99.9% (57M cached / 30K reads)
[OK] Query cache efficiency: 78.6% (5M cached / 6M selects)
[!!] Query cache prunes per day: 483
[OK] Sorts requiring temporary tables: 0% (0 temp sorts / 408K sorts)
[!!] Temporary tables created on disk: 36% (269K on disk / 745K total)
[OK] Thread cache hit rate: 99% (427 created / 686K connections)
[!!] Table cache hit rate: 2% (64 open / 3K opened)
[OK] Open file limit used: 11% (120/1K)
[OK] Table locks acquired immediately: 99% (3M immediate / 3M locks)

——– Recommendations —————————————————–
General recommendations:
Add skip-innodb to MySQL configuration to disable InnoDB
Run OPTIMIZE TABLE to defragment tables for better performance
Enable the slow query log to troubleshoot bad queries
When making adjustments, make tmp_table_size/max_heap_table_size equal
Reduce your SELECT DISTINCT queries without LIMIT clauses
Increase table_cache gradually to avoid file descriptor limits
Variables to adjust:
query_cache_size (> 16M)
tmp_table_size (> 32M)
max_heap_table_size (> 16M)
table_cache (> 64)

The script recommends to adjust or add the following variables in the mysql my.cnf file. The location of my.cnf is normally /etc/my.cnf or /etc/mysql/my.cnf depending on the Linux distribution that is installed on your server.

Open the my.cnf file:

vi /etc/mysql/my.cnf

and increase or set the variables in the [mysqld] section of the file. Mine looks now like this:

[mysqld]
#
# * Basic Settings
#
user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
basedir         = /usr
datadir         = /var/lib/mysql
tmpdir          = /tmp
language        = /usr/share/mysql/english
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address            = 127.0.0.1
#
# * Fine Tuning
#
key_buffer              = 16M
max_allowed_packet      = 16M
thread_stack            = 128K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover          = BACKUP
#max_connections        = 100
table_cache            = 128
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit       = 1M

query_cache_size        = 32M
tmp_table_sizee        = 64M
max_heap_table_sizee        = 32M

Then save the file and restart mysql. After a few hours, rerun mysqltuner and check again if the values are fine now or if the have to be increased to a higher value.

UPDATE sys_user SET passwort = md5(‘admin’) WHERE username = ‘admin’;

The SQL query sets the password to “admin” for the user “admin”, it has to be executed in the ISPConfig mysql database, e.g. with phpmyadmin. If you dont have phpmyadmin installed, then the query can be executed with the mysql commandline utility as well:

Login to the mysql database.

mysql -u root -p

and enter the password of the mysql root user. To switch to the ISPConfig database, run this command:

use dbispconfig;

Now execute the SQL command:

UPDATE sys_user SET passwort = md5(‘admin’) WHERE username = ‘admin’;

and close the mysql shell:

quit;

1) Stop the mysql server

/etc/init.d/mysql stop

2) Start the mysql server manually without permission tables which allows us to login as root user without password:

mysqld_safe –skip-grant-tables &

3) Login into mysql as root user without a password and switch to the “mysql” database:

mysql -u root mysql

Then execute this SQL query to set a new password for the mysql root user:

update user set Password=PASSWORD(‘mynewpassword’) WHERE User=’root’;

(Replace “mynewpassword” with the new root password in the above command).

Then logout from the mysql prompt by typing:

exit

4) Now bring back the running mysql instance into the foreground by typing:

fg

and then press [ctrl] + c to kill the mysql process.

5) Start the mysql server again:

/etc/init.d/mysql start

vi /etc/mysql/my.cnf

and add the line:

log=/var/log/mysql.log

in the [mysql] section of the file. Depending on the Linux distribution that you use, the my.cnf file can be /etc/my.cnf or /etc/mysql/my.cnf.

Afterwards restart mysql to apply the new the configuration:

/etc/init.d/mysql restart

Remove the postfix package from CentOS which does not has MySQL support:

/etc/init.d/postfix stop
rpm -e –nodeps postfix

Download the postfix source RPM and install it:

cd /tmp
wget http://mirror.rackspace.com/CentOS/5.3/os/SRPMS/postfix-2.3.3-2.1.el5_2.src.rpm
rpm -i postfix-2.3.3-2.1.el5_2.src.rpm

Edit the spec file to enable MySQL support.

vi /usr/src/redhat/SPECS/postfix.spec

and change the line:

%define MYSQL 0

to:

%define MYSQL 1

Install a few prerequisites before we build the new postfix RPM package

yum install pcre-devel mysql-devel

Build the postfix RPM with MySQL support:

rpmbuild -ba /usr/src/redhat/SPECS/postfix.spec

and install it.

cd /usr/src/redhat/RPMS/x86_64
rpm -i postfix-2.3.3-2.1.x86_64.rpm

Start postfix and configure it to be started at boot time:

/etc/init.d/postfix start
chkconfig –levels 235 postfix on

Backup

mysqldump -u root -p mydatabase > /tmp/backup_mydatabase.sql

This command creates a backup of the database with the name “mydatabase” in the file /tmp/backup_mydatabase.sql

Restore

To restore the backup, use the command:

mysql -u root -p mydatabase < /tmp/backup_mydatabase.sql