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I’ve read the “perfect server room” answers and a few other similar questions' answers, but I didn’t see any really good answers on how much physical space is the right amount.

Do you keep your racks enclosed or leave them open without fillers, etc?

For every rack, how much open space do you give around it?

How much space from the wall to the first rack do you leave?

Do you connect all the racks together in a row or do you leave open space between each rack?

What about doing square/cluster configurations instead of rows? I’ve seen that in a lot of datacenters these days, either four rack clusters or four racks around a central cluster (usually with networking in the center).

Typically, I see 0-1 ft from the wall before the first rack, just enough space in front to pull out a server (~3ft) and maybe a little bit less behind for airflow.

In general, I’m thinking about smaller offices with 5 or so fewer racks.


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closed as primarily opinion-based by HopelessN00b Jan 21 '15 at 10:42

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up vote 3 down vote accepted

I could tell you what we do here, but there's way too many little details to go in to. What I can do instead is recommend a great book: Build The Best Data Center Facility for Your Business from Cisco Press. Despite the publisher there's really nothing Cisco specific in it. It offers all sorts of great advice as to how to lay out server rooms big and small (although with an emphasis on big) and a lot of the issues involved. It doesn't go in to great depth on every single topic, but still has enough detail to be useful.

I’ve seen that book before and always assumed it was geared towards larger size installations. If it discusses small as well, it sounds well worth the money. Thanks. – David Aug 6 '09 at 2:32
It's come in useful for our 4 rack sized server room at the office, and it's certainly a book that scales :) – Kamil Kisiel Aug 6 '09 at 4:16
I just wanted to thank you again. I've been reading through it and even though it was written in 2005, it's so far been very informative. – David Aug 11 '09 at 5:33

I don't have answers to all your questions as there are many variables. But if you enough racks to have rows of them. Look into hot isle rack design. APC makes great rack/cooling solutions.

Good point, I edited to add that I’m talking about smaller networks. I think there are an entirely different set of design ideas for huge networks. – David Aug 6 '09 at 0:05

Why not consult with the experts? Positioning of racks can not only depend on cooling but fire suppressant and other things. Things which in the end determine if your insurance is valid or not. An interesting discussion but talk to the experts before applying our comments.

Here here! Don't do brain surgery yourself, don't do HVAC or power or fire suppression or other code compliance yourself. – chris Aug 6 '09 at 0:26
Usually I find that building maintenance staff already has plans for cooling and fire and we have to fit their requirements, not the other way around. This rarely conflicts with space organization except when it comes to the amount of power they will provide us (and therefore determining the room's size vs amount of racks we can put inside it). – David Aug 6 '09 at 3:09

The 'ding ding' here is: Consult with your local experts, do what you can afford to do well, and know where your limits are before you hit them.

A bunch of fallacious stuff gets thrown around every time this comes up, like "you must have 24-inch raised floors", or "you must be on a 2nd or higher story of a building" ... anything that says 'must' is probably advice you can safely ignore.

Honest to god, I've seen some dumb stuff in my time. There's a department at my employer whose server admins (we are in a federated/distributed it environment at a large campus where many groups run their own small machine rooms) are known for letting their orange lights (dell kit) blink for months before addressing hardware issues. The main campus machine room once got hot enough that the flooring tiles warped -- without the ops center even knowing until a vendor-managed piece of equipment managed to call the vendor for help, and the vendor rang the ops center to ask what the hell was happening. (I think it peaked at about 125 degrees F.) There are so many single points of failure that I know of that I would probably win any sysadmin ePeen match with a new high score. Yes, it's terrible ... but, like most things related to the internet, it works despite breaking every rule known to man.

Back on the other hand, I've seen some gifted uses of limited resources. One that comes to mind is cooling. It's difficult to get sufficient cooling in a normal space on campus at a decent price without doing some serious improvements to the building's infrastructure. Since some of our buildings are historic, that's not likely to happen. One excellent use of limited cooling power was to vent all hot air to the outside using enclosed racks with APC-brand fan-back enclosures. The entire server "room" (four racks) was sufficiently cooled by a pair of portable units... but (most importantly) all heated air was immediately removed from the building and vented to outside.

Basic rules: Have enough electricity, a decent connection that will support your peak traffic, and enough cooling capacity to keep the servers from reaching thermal shutdown. After that, anything you can put together is just gravy.

Reminds me of the server room that got so hot, the stickers were peeling themselves off the front of the servers and falling to the floor. I was the only one who felt that this was a problem... good times. – Kara Marfia Aug 6 '09 at 12:51

The only advice I'll add is that make sure you have a good meter of space in front of your rack, enough space to get access to the back of every rack and if possible access to at least one side. You can share the space at the front or the back, so you could have two racks facing each other with a meter gap in between. It depends if space is at a premium or not.


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