These two always go hand-in-hand. If the Power to
your server can be stopped by blackout, or over/under voltage can be
supplied to the Server then the Data on it is not safe (see Chloride UPS
systems).
This area also includes Backup Strategies,
regular recovery tests, (how do you know that your last backup can be used
to successfully recover files?) and utilising RAID storage devices for
Data Warehousing.