Our server room’s battery backup consists of a couple of off-the-shelf APC battery backup units, running an ever-expanding collection of servers (about six, depending on what you term a “server”).  Not the optimal solution, but a cost-effective one that was good enough when the server count was lower.

It’s been so good, in fact, that a very long time has past since the runtime on the battery backups was tested.  Today, the test was unintentional.

Fortunately, since server room cooling has become an issue with such an enclosed space being filled with more and more machines, we are finally installing a cooling unit specifically to keep the server room cool.  A big improvement over walking into the server room and starting to sweat almost immediately, to be sure!  However, installing the cooling unit required turning off the power to the server room for a little while.  It was off for a few minutes before I headed up to our all-staff meeting this afternoon, but it was back on before I went to the meeting and the battery backups held just fine.  I knew it would need to be off for a little longer during the meeting, so I hoped the batteries would hold out.  They didn’t.  When you can’t connect to the Exchange server, or even get a new IP via DHCP over wireless, something’s up.  Or, down rather.

I still don’t know how long the battery backups lasted exactly, as everything was already back on when I made it downstairs.  Reboot everything in the right order, and half-an-hour later you’d never know anything had happened.  And with everyone in the staff meeting, I was able to warn them before the meeting broke that I would need to work on the servers for a little while and not to expect it to be operational when they went back downstairs.

It worked out all right in the end, but it’s something I need to address and haven’t had the time or resources available.  Nothing like a little priority-setting all done up nice for you :-)

Anyone have recommendations about on how you go about battery backup selection?  I took the new building opportunity when replacing the core network switches to purchase a Tripp Lite rack-mount UPS unit for each of our three network closets, which so far have worked admirably, were cheaper than comparable APC brand units, and held the network rack up even through this same power outage.

Does it make sense to buy a smaller off-the-shelf UPS for each server, or each pair of servers perhaps, or to purchase one larger unit that can handle everything, even with the sticker-shock price tag?  (Granted, several smaller units do add up themselves.)  I have a feeling I know, but I’d be interested in feedback.