Our web server was largely unavailable between 12:30AM and about 4AM on March 30th owing to one of the system database tables in MariaDB getting corrupted.  I could have restored everything from backups in a shorter period of time but instead loaded backups, rescued the hurt system table structure from backups, then returned the server to the current image and dropped the corrupted table and re-created it from backups up data.  That way no user data was lost.