Open rack vs. enclosed cabinet

  • Thread starter Thread starter Yoann Roman
  • Start date Start date
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Yoann Roman

I'm looking to move my servers to a rack/cabinet in a 7-ft by 5.5-ft room.
About 6 tower servers, 1 rack server, 4 rack switches, 3 routers/telecom,
and 3 non-rack UPS.

Would an enclosed cabinet work in terms of cooling? Any general
recommendations of open rack vs. enclosed cabinet? Not much literature on
the topic...
 
My own experience has been that wire mesh shelving is best - affords
greatest flexibility, easy wire routing, few ventilation problems.
This is the sort of thing I'd recommend:

Available anywhere - google on wire shelving

Racks are good for rack servers, rack routers, etc. but not great for
towers.
Click to expand...

My problem is that the room is fairly small (7 ft. by 5.5 ft) so I would
prefer to have only one solution. I could stack all the rack-based
equipment, but that wouldn't be a very neat solution, IMO.
 
thats like physical security, but i'm not expert when it comes to that

Physical security seems to be the main argument for enclosed cabinets,
whereas better ventilation and easier access to components seems to be the
argument for open racks. But I see those two argued for enclosed cabinets,
too.

And it seems that secured environments I've seen still use enclosed
cabinets, so I figured there must be another reason to have them.
 
I'm looking to move my servers to a rack/cabinet in a 7-ft by 5.5-ft room.
About 6 tower servers, 1 rack server, 4 rack switches, 3 routers/telecom,
and 3 non-rack UPS.

Would an enclosed cabinet work in terms of cooling? Any general
recommendations of open rack vs. enclosed cabinet? Not much literature on
the topic...
Click to expand...

A closed cabinet needs sufficient forced air (fan(s)) to
deal with the thermal load and placement of components in
it. It is not just a matter of open or closed cabinet but
the exact equipment, placement, and closed rack. In
general, either option can work, but-

The room itself also needs active airflow. It is not enough
to just have an HVAC duct that only moves air when temp
deviates. If you had a failsafe 100% on-time blower for the
HVAC and large enough ductwork, it could suffice but
generally one looks at supplimental cooling local to the
room... and the way that's implemented can have a lot to do
with the area surrounding the room, the ceiling above or
floor below, and acceptible noise levels and/or noise
isolation.

Either way you approach the racks or cabinets, the room
tends to need similar ventilation rate, or to put it another
way, sufficient rate and a little excess is better than too
little.

The system/component chassis themselves are generally not
meant to aid in cooling, so whether that chassis is exposed
to outside air or not matters little relative to the front
intake and rear exhaust potential of whatever you choose.
For example, either way the cooling will be worse if you put
several butted-up against a corner wall(s). Some air will
recirculate and how much of an impact that has can depend on
the ambient room temp. Air-conditioning is desirable.
 
and keep in mind that HVAC may be turned off at nights, weekends,
holidays. If the equipment is 24/7, the environment must also be
suitable 24/7. To judge whether you need extra A/C or ventilation,
put an electric space heater (or two) into the room and see how hot it
gets - they typically output ~1300-1500 watts as heat. The PCs are each
putting out ~100-300 watts of heat; the networking gear adds some more;
ditto any VDTs.

As for physical security, a metal or solid core door with a key which
you control affords much more security than a rack with a cheap cabinet
lock that is better suited to protecting a desk drawer from pencil theft.
 
and keep in mind that HVAC may be turned off at nights, weekends,
holidays. If the equipment is 24/7, the environment must also be
suitable 24/7. To judge whether you need extra A/C or ventilation,
put an electric space heater (or two) into the room and see how hot it
gets - they typically output ~1300-1500 watts as heat. The PCs are
each putting out ~100-300 watts of heat; the networking gear adds
some more; ditto any VDTs.

As for physical security, a metal or solid core door with a key which
you control affords much more security than a rack with a cheap
cabinet lock that is better suited to protecting a desk drawer from
pencil theft.
Click to expand...

Thank you both for your input.

Physical security is not a concern here. The room locks and access to the
key is controlled. The environment is secure enough for the application,
too.

My main concerns are:
- to protect the equipment from general dust
- provide a stable physical environment (safe from bumps, hits, etc...)
- have a setup that allows easy maintenance and setup, but nothing regular
- protect against accidental pulling of cables (the room is also the telco
closet open to telco companies)

This is a small/medium business, as you can tell by the number of servers,
so cost is the key. Dedicated HVAC is probably hard to obtain from the
building. Regular HVAC is never shut off during the year, though. There will
be a duct added to the room.

If air flow became a problem, maybe some of APC's air flow products would
help, although the room has no raised floor. It has tiled ceilings, but I
don't think there is much air circulation up there. This will be the only
rack/cabinet in the room and I figured I could center it so that it had
plenty of space on all sides. The rack I'm looking at is a SMC rack on
casters with fully perforated rear door, fan at the top, and perforated
sides on either side of the front door's plexiglass.

With a 42U rack/cabinet, I think I could guarantee at least 1U of space
between each component. I didn't notice any component giving off much heat
other than the UPS's.

I realize this is no where near the ideal data center, but I don't think the
hardware/application demands that type of setup, right?
 
My main concerns are:
- to protect the equipment from general dust
Click to expand...

Air filtration can be necessary. Could be whole-room, could
be on a sealed cabinet, either way if this is a dusty
environment then a service interval needs to be maintained
for the filter inspection and/or replacement.

- provide a stable physical environment (safe from bumps, hits, etc...)
Click to expand...

If people are getting in and hitting the racks, you need
better locks or a guard or pre-employment screening or
something of this nature.

- have a setup that allows easy maintenance and setup, but nothing regular
- protect against accidental pulling of cables (the room is also the telco
closet open to telco companies)
Click to expand...

You can partition things off, demand a telco check-in and
supervision, or have insurance cover any damage, yours or
theirs. It's not a large room so is there even space for
everything you need in it and still the realistic
expectation that a stranger can walk in and service
something? Depends on where you situate everything. We
can't easily do that or advise on it.

This is a small/medium business, as you can tell by the number of servers,
so cost is the key. Dedicated HVAC is probably hard to obtain from the
building. Regular HVAC is never shut off during the year, though. There will
be a duct added to the room.
Click to expand...

I suggest not only a duct but fan local to the room.

If air flow became a problem, maybe some of APC's air flow products would
help, although the room has no raised floor. It has tiled ceilings, but I
don't think there is much air circulation up there.
Click to expand...

There's where a fan comes in. If the fan is exhausting into
the ceiling, then there is air circulation... providing the
room isn't so sealed off that no air gets in but HVAC duct
will help there too. In other words with a localized AC
system the room can be fairly well sealed (except the
back-end of the AC unit itself) but without localized AC,
you'll want the room not so well sealed up, meaning typical
doors over carpeted areas are too much restriction without
*something* else to allow that flow while still keeping the
room secure.
This will be the only
rack/cabinet in the room and I figured I could center it so that it had
plenty of space on all sides. The rack I'm looking at is a SMC rack on
casters with fully perforated rear door, fan at the top, and perforated
sides on either side of the front door's plexiglass.

With a 42U rack/cabinet, I think I could guarantee at least 1U of space
between each component. I didn't notice any component giving off much heat
other than the UPS's.
Click to expand...

Are any of these passively cooled devices? If not, space
between racks should not be an issue, each component should
be self-sufficient in cooing providing the ambient (intake)
air temp is low enough.
I realize this is no where near the ideal data center, but I don't think the
hardware/application demands that type of setup, right?
Click to expand...

Same environment, smaller scale.
 
Are any of the adjoining spaces unoccupied? Perhaps, you could put a
window A/C through a wall and dump the heat 'next door'.
Air filtration can be necessary. Could be whole-room, could
be on a sealed cabinet, either way if this is a dusty
environment then a service interval needs to be maintained
for the filter inspection and/or replacement.





If people are getting in and hitting the racks, you need
better locks or a guard or pre-employment screening or
something of this nature.





You can partition things off, demand a telco check-in and
supervision, or have insurance cover any damage, yours or
theirs. It's not a large room so is there even space for
everything you need in it and still the realistic
expectation that a stranger can walk in and service
something? Depends on where you situate everything. We
can't easily do that or advise on it.
Click to expand...
Unclear what you mean here - You need both a supply duct (will it supply
cold air during the winter heating season?) and a return air duct -
something that will draw the air you've heated up out of the room.
I suggest not only a duct but fan local to the room.





There's where a fan comes in. If the fan is exhausting into
the ceiling, then there is air circulation... providing the
room isn't so sealed off that no air gets in but HVAC duct
will help there too. In other words with a localized AC
system the room can be fairly well sealed (except the
back-end of the AC unit itself) but without localized AC,
you'll want the room not so well sealed up, meaning typical
doors over carpeted areas are too much restriction without
*something* else to allow that flow while still keeping the
room secure.
Click to expand...

Consider removing the doors (or not ordering them); you'll get better
air circulation. If you do order a rack, get roll-out shelves for
towers, UPS, etc - i.e., everything heavy. Consider how you will
service a tower whose access panel is on the side.
Are any of these passively cooled devices? If not, space
between racks should not be an issue, each component should
be self-sufficient in cooing providing the ambient (intake)
air temp is low enough.
Click to expand...

Only you (or your bosses) can decide how critical the application is and how
much money to spend on protecting it.
Same environment, smaller scale.
Click to expand...

I suggest you talk to the building engineer (if such exists) for ideas
and suggestions. You may be building a sauna.
 
Are any of the adjoining spaces unoccupied? Perhaps, you could put a
window A/C through a wall and dump the heat 'next door'.
Click to expand...

The room is surrounded by an office, a storage room, and the office hallway.
I don't think blowing a hole in the wall will be well-seen by the company
execs or building management.

Others have recommended a fan in place of a ceiling tile. I've never seen
any of these around. Anyone used these before? Would they work for this
application? I figure the HVAC vent will bring in cold air while the fan
could take out the cold air.
 
My main concerns are:
Air filtration can be necessary. Could be whole-room, could
be on a sealed cabinet, either way if this is a dusty
environment then a service interval needs to be maintained
for the filter inspection and/or replacement.
Click to expand...


It's not too dusty, really. Right now, the equipment is housed in a regular
office, which is probably the source of most of the dust. I figure that once
this is in an isolated room, the dust will reduce significantly. The
enclosed cabinet was an additional precaution.
If people are getting in and hitting the racks, you need
better locks or a guard or pre-employment screening or
something of this nature.
Click to expand...

The room is also the telco room, so telco guys may accidently hit against
the equipment when working in that room. It's really more of a closet, so
there isn't too much space. It should be fine, but, again, precautionary.
You can partition things off, demand a telco check-in and
supervision, or have insurance cover any damage, yours or
theirs. It's not a large room so is there even space for
everything you need in it and still the realistic
expectation that a stranger can walk in and service
something? Depends on where you situate everything. We
can't easily do that or advise on it.
Click to expand...


From my measurements, space shouldn't be too big a problem. There's only
going to be one rack inside the entire room. The telco stuff is all
wall-mounted and takes up basically no space. The note about preventing
accidental pulling of cables is that, once we know the telco guy is in
there, we don't watch over him/her 24/7. It's too small a room to do so. So,
while they're not idiots, I just want to be cautious.
I suggest not only a duct but fan local to the room.
Click to expand...


I take it this fan would take air out of the room. How would you suggest
installing this? The room is surrounded by an office, a storage room, and
the main office hallway. It has no windows. It does have an acoustic
ceiling, so I could place a fan there, but I haven't come across any such
models.
There's where a fan comes in. If the fan is exhausting into
the ceiling, then there is air circulation... providing the
room isn't so sealed off that no air gets in but HVAC duct
will help there too. In other words with a localized AC
system the room can be fairly well sealed (except the
back-end of the AC unit itself) but without localized AC,
you'll want the room not so well sealed up, meaning typical
doors over carpeted areas are too much restriction without
*something* else to allow that flow while still keeping the
room secure.
Click to expand...

The room does not have localized A/C, but it does have its own HVAC vent. It
is not sealed off very well. There is a fairly large gap under the door that
can aid in air circulation. I'm thinking that a fan in the ceiling may help,
but I'm not sure where to buy such a device.
Are any of these passively cooled devices? If not, space
between racks should not be an issue, each component should
be self-sufficient in cooing providing the ambient (intake)
air temp is low enough.
Click to expand...

One of the switches has no fan (I figured that's what you meant by passively
cooled device). The rest of the equipment has fans, but I've typically been
recommended to have 1U of space between switches/routers and the such. Not
so much with servers, but I plan on doing it anyway as a precautionary
measure, if I have the room.
Same environment, smaller scale.
Click to expand...

My reason for this comment was cost, really. This is a small business, so
cost is a very important factor. Second, this room already exists and has
already been in use for the DMARC and other telco equipment. I'm just
relocating the server equipment into it. Lastly, the room is very close to
offices and off the main hallway, so noise is an issue. I don't want to put
in an air conditioning unit that makes it sound like the room will collapse.
The servers, all combine, aren't noisy enough themselves.

Thanks for the advice/time.
 
The room is surrounded by an office, a storage room, and the office hallway.
I don't think blowing a hole in the wall will be well-seen by the company
execs or building management.
Click to expand...

The company execs then, will need adequately briefed about
the need for the room to be suitable for the purpose... IF
whatever you decide to do requires modifications.

Others have recommended a fan in place of a ceiling tile. I've never seen
any of these around. Anyone used these before? Would they work for this
application? I figure the HVAC vent will bring in cold air while the fan
could take out the cold air.
Click to expand...

Such a fan should have a bracket and be supported from
above, not just a hole cut into a ceiling tile (if that were
what you were thinking of based on my non-descript concept).
Would just a hole work? Maybe, but I wouldn't count on it
without knowing the rigidity of the ceiling or any other
unforeen variables... I'd plan on a very secure mounting.
As for building management, they might not like a fan
either, you might have someone keen to lease/legal issues
look over details this impinge... in other words such a
project should be done with all having full knowledge of it.
 
I think there's some confusion about air circulation and HVAC. Often,
the space above a drop ceiling is an air plenum, pulling 'used' air back
to the fans (and heating/cooling equipment) for the building. At other
times, duct work is used to pull the air back (return air as its
called); in this case the space above the ceiling tiles is just dead
space. You've got to determine whether your ceiling is a return plenum
or whether it is just dead space. Go into a room near your proposed
server room that has two grills, probably one in the room's center and
one at the periphery. The center one is probably supplying air while
the one at the edge is probably pulling out 'used' air. A Kleenex on a
stick will show which way the air flows. Then investigate whether the
return air grill is tied to duct work or is just a hole in the ceiling.
If you have an active plenum, then one supply duct at one end of the
server closet and a hole in the ceiling at the other end might provide
sufficient ventilation. If the ceiling is dead and a return duct can't
be installed, perhaps louvers in the door would let the heated air
escape. Putting a fan in the ceiling blowing up might help a little but
I wouldn't count on it. Just get a $20 box fan at K-Mart, cut a hole in
the ceiling tile, and lay the fan on the tile. If you want, you can tie
some strings to the fan and to the ceiling tile hangers for extra security.

And I repeat an earlier question - do you know for sure that the
building will be supplying cold air during the heating season?
 
I think there's some confusion about air circulation and HVAC. Often,
the space above a drop ceiling is an air plenum, pulling 'used' air
back
to the fans (and heating/cooling equipment) for the building. At
other times, duct work is used to pull the air back (return air as its
called); in this case the space above the ceiling tiles is just dead
space. You've got to determine whether your ceiling is a return plenum
or whether it is just dead space. Go into a room near your proposed
server room that has two grills, probably one in the room's center and
one at the periphery. The center one is probably supplying air while
the one at the edge is probably pulling out 'used' air. A Kleenex on
a
stick will show which way the air flows. Then investigate whether the
return air grill is tied to duct work or is just a hole in the
ceiling.
If you have an active plenum, then one supply duct at one end of the
server closet and a hole in the ceiling at the other end might provide
sufficient ventilation. If the ceiling is dead and a return duct
can't
be installed, perhaps louvers in the door would let the heated air
escape. Putting a fan in the ceiling blowing up might help a little
but
I wouldn't count on it. Just get a $20 box fan at K-Mart, cut a hole
in
the ceiling tile, and lay the fan on the tile. If you want, you can
tie
some strings to the fan and to the ceiling tile hangers for extra
security.

And I repeat an earlier question - do you know for sure that the
building will be supplying cold air during the heating season?
Click to expand...

Thanks for the clarifications. This helps a lot!

I'll check on the active plenum vs. return vents. From what I've seen by
poking around, there are a few ceiling tiles that are just perforated and
have no duct work attached up in the ceiling. I don't know if these are
potential HVAC ducts that have not been hooked up or proof of an active
plenum.

I doubt they will be supplying cold air during the heating season.
Unfortunately, the building duct work isn't advanced enough to separate hot
& cold vents. I did change my decision and will now use open racks. I figure
if it gets too hot during winter, I can just block off the vent and install
a fan into the ceiling like suggested.

Thanks again for the tips.
 
Yoann said:
Thanks for the clarifications. This helps a lot!

I'll check on the active plenum vs. return vents. From what I've seen by
poking around, there are a few ceiling tiles that are just perforated and
have no duct work attached up in the ceiling. I don't know if these are
potential HVAC ducts that have not been hooked up or proof of an active
plenum.

I doubt they will be supplying cold air during the heating season.
Unfortunately, the building duct work isn't advanced enough to separate hot
& cold vents. I did change my decision and will now use open racks. I figure
if it gets too hot during winter, I can just block off the vent and install
a fan into the ceiling like suggested.

Thanks again for the tips.
Click to expand...

Installing a fan in the ceiling will not help very much unless you have
a supply of cool air from somewhere. Consider louvers in the door as a
source of cool (70F) supply air during the winter. Keep in mind that to
ventilate your heat sources you need to supply cool air to the closet
and suck out hot air from the closet.

I urge you to get some expert help on this. Convince your bosses that a
proper environment is a legitimate cost of business, just as the
computers are. And don't forget to add the lighting in the closet as
yet another heat source.
 
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