I'm faced with the task of buying some servers (3) and a server rack on which to store them all. Our main requirement is that the server rack is enclosed and lockable so no one can easily walk off with one of the servers. (We also need to do our best to prevent someone from walking off with the entire rack.)
I've never bought a server rack before so I don't know which vendors are reputable or really how to go about it at all. What is your advice?
While HP/IBM/Dell etc sell their own racks they're often just rebadged Rittal racks. Their standard racks are just perfect for 99% of jobs but they also make a 'secure' rack that I buy for certain applications. They're not only stronger but can be tied to the floor and have lots of clever electronics inside such as digital and remotely controlled door locks, cameras facing front and back as well as vibration and anti-tamper alarms - all SNMP/HTTP controlled too. I can't recommend them high enough.
The answer is going to vary widely on your requirements, which since you're new to the game, you may not be entirely aware of.
To the best of my knowledge, square holes are pretty much the standard everywhere. I can't think of any single server we've had that shipped rails with circular holes. Still, this is a possible consideration that you'll need to evaluate when you decide on servers.
A "U" is a "unit" of measurement for racks. Servers come commonly in 1U, 2U, 3U, 4U sizes, and larger things like high capacity storage, high end switches, blade servers, etc. can be taller than 4U. Figure out how many U's your 3 servers use, consider expansion if necessary (and other appliances like switches, kvm's, and the like), and you have your rack size.
We have a handful of 42U racks (which is more or less the common full size rack height), a single half-rack (24U), and a rack on wheels mobile (sorta) unit which is either 8U or 10U.
One of my first jobs where we had a formal datacenter, we bought a solid door rack. I believe it was some kind of plastic on the front and back doors (the side walls are always solid, but removable). The only holes were in the bottom of the rack, and the top. IIRC we had raised floor ventilation, the theory being that hot air rises and exits the rack. Don't bother with these racks, we lost a couple of servers, and nearly burned our hands trying to move other ones. I'm a huge advocate of front to back airflow (assuming your airflow is adequate).
I'm foregoing my recommendation because they don't make small racks, and if you're looking for only 3 servers (+1U for a switch?) this company doesn't make racks shorter than 24U to the best of my knowledge.
For what it's worth, some vendors, like HP offer slightly wider racks than the standard 600mm, e.g.: http://h10010.www1.hp.com/wwpc/uk/en/sm/WF06b/3447589-3447589-3446288-3446293-3446293-1155226-3360116.html
The extra 10cm each side of the server gives you a decent sized cable duct.
Also, don't forget to get a modular power setup, i.e.: 32A power units with IEC socket units hanging off it, running vertically up the rack. This allows you to keep your power cables nice and short. HP's offering is here: http://h18000.www1.hp.com/products/servers/proliantstorage/power-protection/power-distribution/modular_pdu/questionsanswers.html
If you're positioning the rack in an existing room, think about which direction to orient it. Most ISS kit breaths from front to back. You don't want one rack's "exhaust" pumping hot air into the front of your rack.
Also, do you need KVM equipment, or are you running it as a dark rack (relying on the servers' remote management interface).
Don't discount companies like COOPER B-Line in Somerset (http://www.cooperbline.co.uk/), who do some cracking rack equipment; they'll even create bespoke racks, with all sorts of security features.
