innodb force recovery

innodb_force_recovery.txt

FROM: https://serverfault.com/questions/592793/mysql-crashed-and-wont-start-up

Ouch.

InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/5.1/en/forcing-recovery.html
InnoDB: about forcing recovery.

Check the suggested webpage: http://dev.mysql.com/doc/refman/5.1/en/forcing-recovery.html.

Basically, try to start the MySQL server in a recovery mode and make a backup of your crashed tables.

Edit your /etc/my.cnf and add:

 innodb_force_recovery = 1

...to see if you can get into your database and get your data / find the corrupted table.

Usually, when this happens it's a re-build (at least of a corrupted table or two).

From http://chepri.com/mysql-innodb-corruption-and-recovery/:

    Stop mysqld (service mysql stop).
    Backup /var/lib/mysql/ib*

    Add the following line into /etc/my.cnf:

    innodb_force_recovery = 1

    (they suggest 4, but its best to start with 1 and increment if it won't start)

    Restart mysqld (service mysql start).
    Dump all tables: mysqldump -A > dump.sql
    Drop all databases which need recovery.
    Stop mysqld (service mysql stop).
    Remove /var/lib/mysql/ib*
    Comment out innodb_force_recovery in /etc/my.cnf
    Restart mysqld. Look at mysql error log. By default it should be /var/lib/mysql/server/hostname.com.err to see how it creates new ib* files.
    Restore databases from the dump: mysql < dump.sql