Tables in an inconsistent state.
THE SYMPTOMS
Tables marked as crashed Errors when reading specific rows Data that appears and disappears Repair operations failing
THE CAUSES
An interrupted write, usually from the server or process being terminated Disk space exhausted during a write A very large operation terminated partway
REPAIRING
phpMyAdmin: select the table, Operations, Repair table.
This resolves most single-table corruption without data loss.
IF REPAIR FAILS
Restore that table, or the database, from backup.
IF IT RECURS
Check disk space first. A full account causes writes to fail partway, which is the most common cause.
Check inodes too.
If it continues with adequate space, open a ticket. Repeated corruption may indicate something server-side.
BEFORE REPAIRING
Export the table if you can. Repair usually works and occasionally loses rows.
PREVENTION
Keep disk and inode usage well below the limits Avoid terminating long operations partway Keep backups, which make the whole question less serious
