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I have a couple of Dell 1U rackmount servers that I need to temporarily move out of a rack.

Is it bad for them to be stacked on top of eachother?

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8  
It makes it really tough to get the top panels off for servicing them. :) –  jscott Oct 18 '11 at 20:18
    
Well yes, I suppose I'm asking if stacking them is liable to cause an increase in the likelihood that they need to be serviced. –  Chris Oct 18 '11 at 20:20
    
It sounds to me like you're talking about a temporary situation only. Correct? –  John Gardeniers Oct 19 '11 at 20:57
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4 Answers

up vote 13 down vote accepted

Not really. I've got 4 Dell PowerEdge servers stacked one on top of another right now. There's really no risk of collapsing the bottom servers from the weight of the top servers and there's really no risk of overheating, as the servers draw cool air in the front and exhaust hot air out the rear.

The risk is that the platform you're putting them on could collapse if it can't bear the weight of the servers. The only other issue, as jscott pointed out, is the inability to access the innards without moving them off of each other.

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My experience with stacked (as opposed to properly rack-mounted) hardware is that the machine on the bottom becomes inherently unreliable in ways that require you to open the case (bad RAM, dead fans, etc.) -- Murphy's law stalks the server room –  voretaq7 Oct 18 '11 at 22:14
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Of course this answer presumes that the servers have enough structural integrity to support the additional load on the chassis. Dells sometime do and sometimes don't... –  Jim B Oct 18 '11 at 22:30
    
That could be but I've had four 8 year old Dell PE servers stacked on top of each other for 5 years with no ill effects. –  joeqwerty Oct 18 '11 at 22:33
    
some of the newer dell servers (dell r710s come to mind) will flex enough to put pressure on the riser card and cause weird errors. I've also seen r710s stacked and have no issue. –  Jim B Oct 19 '11 at 5:12
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If they are just a couple servers and if they are 1U, stacking them on top of each other should do them no harm at all.

Of course, it's quite a less-than-optimal placement... but if it's temporary, I see no problem in doing that.

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From a mechanical engineering standpoint, I'll add that you want to make sure the server on the bottom has its bottom surface supported as evenly as possible. This would normally mean putting it on a sturdy flat table or countertop that extends past both long edges of the case. And if its front panel projects downward even slightly below the bottom of the case, position it so that edge of the panel just overhangs the edge of the table.

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To be really clear, only the two side edges need to be properly and evenly supported and the side vertical faces of each unit kept reasonably well aligned. If the front panel does project above or below the height of the side then use something, such as pieces of wood, under the side edges of the bottom unit and at the side edges in between units. –  John Gardeniers Oct 19 '11 at 21:05
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They can only handle so much weight, their boxes aren't designed to have a lot of load on them. If we're talking 3 or 4, I wouldn't worry, but I'd worry past 4.

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can vouch for 6-7 3U servers with no problems. they're built really well to be honest –  Sirex Oct 18 '11 at 21:10
    
@Sirex You had 18-21U just stacked on top of each other? –  MDMarra Oct 18 '11 at 22:09
    
yes ? When moving server rooms had 3 half rack loads in 3 piles. No problem at all. –  Sirex Oct 27 '11 at 12:02
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