Physical and Environmental Considerations
The location and physical security of a server system is one of the first things to consider when putting a system online. Your needs may not dictate that your server be in a secure Tier 4 co-location facility, but your servers may need to be at least in a locked and controlled access room in the back corner of your office suite. The bottom line is that you can't certify a system secure if it is in common access kitchen that you share with 4 other businesses.
Many IT departments have a safe place that they put the core of their network in. Reliable power and cooling are needed to keep your systems running 24 hours a day 7 days a week. If you are able to co-locate your servers with a service provider then make sure that you have the physical access that you need in case of emergency and after hours needs. Service level agreements with your provider will help ensure that you get the help you need and that when something happens your organization is not left holding the bag.
Environmental concerns should be considered such as flooding and fire protection. Hardware should be placed off the floor to prevent suceptibility to local water pipe flooding. If you can place equipment higher than that, then you are even better off. In 1997 one of the facilities that we were working at had a water main break in the back of the building. Although the water main break was 10 feet below the ground, the water pressure created a large hole, compromised the concrete foundation of the building and mud and water poured into the rest of the building. When workers arrived the next morning they found 6 inches of mud and muck throughout the building. Though there was severe damage to the facility most critical equipment was spared simply because it was elevated off the ground.
Users desktops should also be elevated off the ground for the same reason. Telecom equipment in data closets is typically wall mounted on back boards and should also be positioned at comfortable working heights well off the ground.