Check the log files. If you find InnoDB database corruption, follow the below mentioned steps:
Take a backup or mysql directory, which can be used to restore if anything goes wrong.
# cd /var/lib/
# tar -cxvf mysql.tar.gz mysql
//Stop mysql service
# /etc/init.d/mysql stop
Add the following line into /etc/my.cnf to make mysql read only
innodb_force_recovery = 4
Restart mysqld - Mysql will start as we have started in read only mode
//Take backup of all databases using mysqldump
# mysqldump -A > alltable.sql
Drop all databases which are corrupted
Database can be deleted by deleting related directory in /var/lib/mysql/ or from mysql command-line or from phpmyadmin
#mysql -u root -p
# DROP ;
//We can check available database using this command
# show databases;
//Stop mysql service
# service mysql stop
//Remove innodb log and data file
# rm -rf /var/lib/mysql/ib*
Remove or comment out innodb_force_recovery in /etc/my.cnf
//Start mysql sevice in read-write mode
# service mysql start
//Restore database from backup that we have taken
# mysql -u root -p dbname < alldb.sql
After restoring DB restart mysql. We have fixed the issue, if MySQL is able to restart successfully. If still issue persists, you will need to restore database from older backup.
