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tsmerian
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Server Racks Half Full???

Just wondering if any of my fellow peers have encountered this one...

Our building facilities group is making a move to only fill our servers racks to half capacity. They claim that the reason for doing so is to cut down on the amount of heat concentrated in a small area.

Now I'm no HVAC expert, but my BS detector is going off here... While I'll admit that it may disperse the heat, it doesn't cut down on the total amount of BTUs generated. We currently use 42U racks (those are the most common right?), and standing behind a full rack of them will make you sweat, but we are not getting any temp alerts on any servers. Our group claims that they have been to seminars that suggest the practice of using half capacity racks.

I'm asking if anyone out there is doing this... It seems very discouraging to think of using up all the floor space that I helped to free up (with virtualization) in the datacenter by only filling up racks half way!

Theo

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esiebert7625
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A proper data center design consists of hot aisles and cold aisles. If you have proper cooling and ventilation and your vent tiles in the right spots you should not have any issues providing you have enough cooling capacity for the amount of heat your systems generate. Filling up racks half-way is just a waste of space. The below doc illustrates this...

http://docs.sun.com/source/816-1613-14/Chapter3.html

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Grasshopper75
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BS is right.

The only reason I could see someone doing this is to disperse weight not heat. We have an issue with weight in our datacentre because of the weight on the floor and building structure.

Very weird policy. And why buy 42U racks if you are going to do that? Can you still get 22U racks these days? You used to back in the days of Compaq (before HP).

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esiebert7625
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A proper data center design consists of hot aisles and cold aisles. If you have proper cooling and ventilation and your vent tiles in the right spots you should not have any issues providing you have enough cooling capacity for the amount of heat your systems generate. Filling up racks half-way is just a waste of space. The below doc illustrates this...

http://docs.sun.com/source/816-1613-14/Chapter3.html

Eric Siebert

VMware Communities User Moderator

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Visit my website:

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CoreyIT
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I have seen a number of customers configure their racks with leaving 1U of space between each server and using blanking panels to fill the gaps. On older servers that did not have some confluent vacume as newer servers with improved air flow dynamics it was advantageous due the heat that would generate on the top of the case and as such heat the bottom of the server case above it. This is not much of an issue anymore though.

If they are refering to half filling a rack i could see that being the case. If they are refering to stacking servers one on top of each other with no spaces from 0u to 25 u or so and leaving the top half empty than that is silly.

. . . . . . . . .

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ejward
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I know, according to Dell, you can fit 42 1-U servers in a rack without any heat issues. Of course that assuming that your datacenter is not 90 degrees. We have a Dell rack with 36 1-U servers with no issues.

Do you have a cooling problem now? Buy one of those laser thermometers and see if you have any hot spot. There's a craftsman one out there at Sears for $30.

Do you think somebody is getting a kick-back for buying racks?

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mikepodoherty
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I've been in data centers that were row upon row of racks completely filled with 1 and 2 U servers.

If an AC unit had problems then the fans were brought out but I don't ever recall seeing a temperature issue.

Now, the systems I support are primarily in blade chassis - IBM chassis = 70 servers in the rack - different type of cooling and power requirements but again the only times there are issues are if an AC unit fails - and since the AC units are as new as the blade centers, this hasn't happened yet.

I think we are all assuming that you have your servers in a computer room that has been properly designed and built. I recall some small business customers where I wouldn't fill a rack - but that was because they converted a closet to support the computers and did not have proper computer room with sufficient cooling and air flow.

ejward
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I think we are all assuming that you have your servers in a computer room that has been properly designed and built. I recall some small business customers where I wouldn't fill a rack - but that was because they converted a closet to support the computers and did not have proper computer room with sufficient cooling and air flow.

I had the same thing where a department decided to put servers in an old darkroom. One or two were fine. In the summer when they had 4, they had issues.

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