Check local fire-codes. Really. In 2003 I was involved in setting up a new data-center for my old job. My job was more moving the gear safely and setting it up in the new location, not wrangling with the architects and contractors who were building it.
Imagine my surprise when I found sprinkler heads in the data-center during my first walk through. I got about a quarter of the way to indignant outrage before my boss short-circuited me with logic. It seems that local fire code actually covers data-centers, and it mandates sprinklers. I was assured, assured I tell you, that they wouldn't go off unless the FM-200 system failed to snuff the fire. I was dubious, but the fire inspectors really did mean that.
Anyway, there are a series of things you need in a fire suppression system.
- An Emergency Power Off function If there is a fire, the EPO will drop power to the room hard. Yes, that'll cause data damage, but so does fire. If the fire is electrical in nature, this may stop it. Also, if all the gear is de-powered, a water dump does less damage.
- A sealed room You want sealed for correct HVAC anyway. You don't want to rely on building HVAC unless the building was designed with that room in mind in the first place. Also, this allows you to use...
- A gas-based suppression system FM-200 is popular choice for this. Unlike the halon systems of old, it isn't as environmentally evil and doesn't leave a mess behind. OldJob had a Halon dump in the 80's due to a burned bag of popcorn ("The $20,000 bag of popcorn"). It was... bad.
- A water based backup suppression system If the FM-200 fails, you need to get the fire out. After the EPO has fired, and the FM-200 dumps, if there is still a fire then you need old fashioned water
- Water detection sensors in/on the floor If you have any water pipes overhead, you need water sensors in the floor. This is more of an asset-protection thing, but if you DO have sprinklers you need water sensors to detect leaks. Also good for detecting leaks in your HVAC chillers.
- Call-out capabilities If the fire system trips, you want to notify both Facilities people, as well as data-center staff and management. Obviously, this system should NOT rely upon assets in the data-center that's on fire. This can be hard.
There may be more, but that's off the top of my head. The EPO can be a destructive option, so I don't know how wide-spread they are. But they make all kinds of sense in a room where a water dump is possible.
If you have to retrofit a pre-existing room, some of the above may not be possible. As a fire-inspector once told me, to extinguish a fire you need one of three things:
- Remove the fuel
- Remove the oxidizer
- Cool the reaction below the combustion point
The system I lined out above does all three. The EPO removes fuel and can cool the reaction to below the combustion point. The FM-200 partially removes oxygen, but mostly cools the reaction below the combustion point. The water dump smothers the fire due to lack of oxygen, and also cools it. For a high-value asset like a data-center, you want at least two of these.
Because of this, I'd say that your top priority is to see if you can get a gas-based extinguishing system in place as it does far less damage than water does (even with an EPO on your power-distribution-unit or main breaker panel). A truly good system, no matter what the actual suppression technology, has a flexible notification system that allows more than just the facilities supervisor to be notified of the fire-suppression systems activating.
As for hand-held extinguishers, use Class C extinguishers. But be careful. Dry chemical style extinguishers blow a powder everywhere. And that powder is somewhat corrosive. In the typical high airflow data-center, a fired extinguisher's residue can get everywhere. If the powder gets inside server intakes, it can cause higher equipment failure rates for the next several years and the total cost may be more than the system that was on fire. We've had demonstrations of extinguishing fires at our workplace, and have seen how messy it can get. When you buy your extinguishers for in-center usage, use the gas-style Class C extinguishers.