All databases are backed up once per day, and retained for seven days. Backups are not directly accessible by members at this time, but if you need a copy of one of your database backups open a Bugzilla ticket under the SQL DBs component, making sure to note which date you want a backup from, and an admin will copy the database to a secure directory in your afs home directory.
MySQL backups are stored as sql dumps, and PostgreSQL backups are stored in the native PostgreSQL dump format.