Determining the required depth and specifications for a server cabinet
- by Bingu Bingme
I'm trying to understand the considerations ("why") that go into determining the specifications ("what") for a rackmount server cabinet, in order to determine what sort of rack I should purchase for my home use. Since this is for home use, I won't be following certain best practices (eg. hot/cold aisle, not even air conditioning) and may be willing to sacrifice in various areas in order to reduce cost and footprint - but please advise if there are safety concerns or other considerations to note.
The most basic specs for a server cabinet are the dimensions (external width x external depth x usable height).
Width: commonly 600mm or 800mm (if the use case requires extra
clearance around the sides, such as if there is lots of cabling). In
my case and most common cases, I'm going to stick with 600mm.
Height: Select a sufficiently tall rack to fit my equipment. But how much may I stuff into it? Eg, if there is a 15U rack, can I really populate it with 15U of servers, or should I leave 1U at top and bottom for air circulation?
Depth: Racks commonly have external depth of 600mm (network equipment), 800mm, 1000mm, or even longer. I'm trying to see how to fit into the 800mm depth. With reference to http://www.server-racks.com/rack-mount-depth.html, I'm hoping to have the front and rear posts mounted ~ 28.5" (72cm) apart, which would leave only 8cm for front space and rear space. How much rear space (from rear posts to back of rack) do I really need? I won't use cable management arms, so can I mount a 72cm depth server since the power, KVM, network cables won't take up much depth?
My most important equipment are all < 60cm depth (4U chassis) and should comfortably fit within the 800mm cabinet. The rest of the equipment are very old 1U servers that range from 65-72cm depth. I might still want to make further use of them, or I might discard them since they are so old. Even if the 72cm servers cannot be powered on in an 800mm rack, I should be able to use them as 1U shelves. But, what server depth can I expect to be able to operate? Or am I forced to upgrade to 1000mm depth racks in order to use any servers deeper than 60cm?
With reference to best practices for HP racks, some other specs and installation considerations:
There aren't any minimum recommendations for clearance on the sides of the rack.
It is recommended to leave 48" front clearance. The 48" front clearance is based on 32" chassis depth, 13" to extend the rack rails and mate the inner/outer rails, and 3" for movement. If I don't use such rails (eg, use shelves instead), it should be sufficient to leave front clearance of chassis depth + 3".
It is recommended to leave 30" rear clearance "to provide space for servicing the rack". I'm planning to back the rack into a corner of the room, and wheel it slightly out when I need to access the rear. If the wheeling plan is ok, I still need to know how much rear clearance is required for air circulation and ventilation purposes.
Castor wheels and stabilising feet. Since I'm backing the rack into a corner of the room, I'll only be able to set the stabilising feet on the front corners. Thoughts on safety?
The rack that I'm considering has front glass doors with side ventilation slits and fully perforated rear doors. I'm hoping this will be a good balance between temperature and noise (only ventilation slits facing out the front, while the rear is facing the walls). Or is the sound of high-rpm fans going to escape through the front slits anyway and destroy my sanity?
