Oh, and please disregard Sip when he talks of overkill. No such thing as too much protection. Once the dominos start falling....
Example:
DB driven E-commerce web with a MySQL database.
Linux server running 2 HDs in RAID - with 2 DBs (one mirror) on the same machine.
Cron job to copy the DB to the dev server (in the same cabinet) once a day.
Cron job using RSync to transfer the DB to a remote server location every 4 hours.
The remote server backups the DB onto a Exabyte Tape Backup drive, with a full backup one weekly, and incemental backups daily.Media in the tape drive is on a weekly rotating schedule with enough tapes for 6 weeks.
At any given time, there are 4 'relatively' updated copies of the DB in separate locations (main server, dev server, remote server, last set of tapes)
You'd think it was bullet proof.
Short answer, NO! Disasters happen.
Lost 1 week of data - and 3 days downtime, + labour cost for rebuild.