How large should a UPS be for a server room?

Question

How large should a UPS be for a server room?

Answer 1

For servers, you would have a UPS (or UPSs for each unit) that can run everything for the duration between the power failure and your backup generator taking over (most automatic standby generators start in 20-30 seconds when operating properly).

The size will largely depend on how long of a backup you need/want, how many servers are plugged in, how many drives they have, and how much work they're doing.

Don't forget to provide UPS power for your network switches if you expect things to keep talking to each other!

Here's a tool to help you figure out what you need:

http://www.apc.com/tools/ups_selector/

Answer 2

You really need one UPS per machine. If you need to support a server room with multiple machines for any period of time, a UPS is not the answer. You really need a backup generator.