Today, there are many different pieces in the video server puzzle. Instead of videotapes, most servers are using disk-based storage to provide digital information. It probably doesn't matter which method is being used, as long as the system can be considered scaleable. This requirement comes from a simple truth - no matter how much storage you have available today, you need more tomorrow. Any product that wants to be called a server must have a way to expand in the future.
Redundancy is an issue that usually goes along with scalability.
As a system grows over time, it's important that your information is protected. Many companies have learned the hard way about the problems of old videotape, but digital storage is not immune to problems. Some servers are designed for short-term storage and may not include any type of extra data protection. How important this is for your facility depends on what kind of information you are serving and whether there is any type of independent backup system in place. Another issue is the format of the stored material.