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Racked by Data Center Doubts

Members of the ISP-Colo list provide advice on one of the biggest decisions an ISP makes when setting up a data center: do you use racks or cabinets, and why?

[August 21, 2001]

On the ISP-Colo list in July, NC inquired,

"We are opening a datacenter, and we need to decide whether to use open racks or cabinets. Any ideas?"

Many respondents suggested covering both bases:

[JR advised] "Both. We used cabinets at first, but when servers started getting longer, we had to buy racks. It's all about the money and the space."

[KF agreed] "I see a lot of racks and cabinets; each have strengths and weaknesses."

Others raised two key issues to consider, cooling and cable management:

[KF cautioned] "When selecting either, first look at the layout of your cooling systems. I have seen a number of instances where this was not done, and companies have had to get box fans to blow air into cabinets or across racks. This is a complicated subject to get into, but there's an excellent white paper here."

[JP added] "Just as important as cooling is cable management: both data and power cables. Both racks and cabinets have pluses and minus. One other factor is that if you are building in a seismic area, bracing may play a factor on your choice, or at least on the arrangement of the units."

[LM agreed] "Cable management and cooling are very important. If you go with cabinets, do not get glass or plastic front doors; they cut down on airflow. I recommend full mesh on both front and back. Running your cable overhead instead of under raised flooring works much better as well; it will force you to keep it under control because you can see it."

Still others noted that the number of factors to keep in mind can be dizzying:

[BN offered] "I would stay away from cabinets if you don't have a raised floor; it's just too hard to keep cool.

If you have a lot of clients in the same cage, cabinets provide better security.

If you have deep equipment, I would get deep cabinets, as deep equipment and racks don't work out so great; you have to get another set of racks in the back, and either mount them just right or get a shelf. You would not want to mount all of the weight on the rack without a rear support.With cabinets, you have back rails that are easy to move around, and are cheaper than installing another set of racks. Remember, though, there are consulting firms out there that will help you build a facility, and it will save you many headaches. There are lots of different codes that you must meet with your city when you build out a data center."

[BT added] "Some customers may want racks; some may want to bring their own cabinets.

• Routers tend to mount well in standard racks; some may take a little effort.
• Servers, especially when they get deep, seem to do better in cabinets, either rack mounted or on shelves.
• Cabinets are definitely harder to keep cool than open-frame racks. You'll have the easiest time with forced air coming from under the raised floor, into the cabinet through as large a cut-out as you can make.

If you're not going to hire someone with experience to do this for you, I'd advise you to look at a lot of other people's spaces, see how they set them up, and talk to them about what they'd do differently next time and why."

— End