Correct temp for a Cabinet.

[knightred]

I have servers in 42u cabinets with mesh doors and wondered what the correct temp inside a cabinet is. The cabinets have about 24 - 30 servers in each. one is around 22C/72F and the other around 28C/ 83F inside the the cabinet. Is this good? What is dangerous like 90-95F, considering this is the temp inside the cabinet on top of the stack of servers.

[brownm521]

your temps sound about right. I would say if your temp rises above 90 degrees at the server exhaust , you may want to remove some servers or have your colo provider install grated tiles in front of your cabinet.

[jaybirdsmith]

Usually the temp is going to differ where you read it.

If you read it on the front, then ~70 is good. You should see a higher temp at the back, ~85.

What it reads on the top or bottom is somewhat pointless. Its what your intake and vent temperatures are that is important.

[Wallerich]

Data center thermals is a huge issue these days, thanks to blades, salesman who sold high density as a TCO benefit, and changes in application deployments.

Most servers exhaust air in the 95F range. The issue is supplying enough cold air across a rack to provide adequate cooling. Most data centers have terrible thermal dynamics, with as much as 30% of the hot air contaiminating the cold aisle (I'm assuming hot aisle - cold aisle here). There are a number to tricks, but the basic rule is to never have open spaces in your rack - fill them with blank panels. Under floor temp should be 55F or so. Room temp should be in the 75F range.

Put higher density/power servers near the bottom of racks, don't concentrate high density racks in same area. This gets into complex discussion of under floor air pressure management. Expensive tools are required for larger data centers.

Also, be aware that the closer your equipment is to the CRAC, the less cooling capacity you'll get. The highest pressure is always furthest away from the CRAC, not right next to it. If you have the rack space, propagate the bottoms first, fill the tops with blank panels. Your equipment will live longer and you'll spend less to cool it.

John

[raid]

The most important thing about temperature is not how hot the exhaust is, but what’s the temperature of the inlet air and how it is measured. You should get a copy of the following publication from the ASHRAE web site.

“Thermal Guidelines for Data Processing Environments”

The second thing you need to do is get the Data Sheets on the IT equipment installed in the racks. Network equipment, servers and tape libraries will have very different requirements so you will need to understand what’s required.

Armed with this data you should be able to determine if the temperature will be within operating range.

To understand if the hot air is circulating within the equipment, try this simple test:

Place your hand on the mesh at the bottom of the front door; it should be cool to the touch. Move your hand up the rack, and as you do any warm sections of mesh will correspond to warm air circulation from the back of the rack. (you will be supprised how many people install equipment in the wrong way around, usually because it’s easier to cable)

Some racks have areas at the side of the rack that also allow the air to circulate; again if you move your hand to the side of the door you will find that the mesh is warm.

“A rule of thumb is that long-term electronics reliability is reduced by 50 percent for every increase of 8 degrees above 21 degrees” Uptime Institute.