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We're moving in to a new building, soon. Most of the building has a raised access floor consisting of 600x600mm square tiles; galvanised steel-coated MDF. (The closest equivalent I can find is Tate Woodcore.) These tiles are pre-drilled and screwed at the corners to supporting stacks on the concrete floor. The void is about 4".

The comms room, on the 2nd floor, also has these tiles. Our specification was that they would bond a hard-wearing, anti-static vinyl on to the individual tiles such as to allow them to be lifted easily at a later date. It now transpires that this isn't a good idea, since the vinyl would have to be cut to fit and would be prone to damage and rucking at the tile corners.

The choice I face now is to either replace the floor tiles entirely with something more suitable, or to simply polish the existing bare tiles and stick with those (the latter is actually how we found the room).

Bare tiles would certainly be easier and cheaper, but will a bare metal floor cause me any problems that I can only mitigate by replacing them?

Notes

  • There is no ventilation requirement in the floor void. There is only power, fibre and a lot of Cat6.
  • We'll have ~4 tons of cooling from two ceiling mounted A/C units
  • At full capacity, we'll have 4 cabs (3 servers and an MDF). Nothing else will be stored in the room.
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Only 4 inches clearance under the floor in your server room? That's gonna start sucking hard as soon as you need to cable runs underneath it. –  HopelessN00b Oct 2 '12 at 17:30
    
@HopelessN00b. 4 inches is a normal standard for underfloor office wiring - and in a DC with overhead cooling, it shouldn't really present an issue. –  Ben Lessani - Sonassi Oct 2 '12 at 17:32
    
@SmallClanger - this makes for interesting reading, esdtile.com/charged-questions/… –  Ben Lessani - Sonassi Oct 2 '12 at 17:36
    
@HopelessN00b It's not that bad, actually. All of our cat6, power and services are in place and there's plenty of room. –  SmallClanger Oct 2 '12 at 19:55

3 Answers 3

up vote 18 down vote accepted

No problem, as far as I know. I have been involved in 2 server-room builds with similar floors a couple of years ago. Never had any issues besides that metal may be a slip-hazard. It it is too slippery you can always apply some anti-slip coating over the tiles.

I do have a few recommendations though:

  • It can't hurt to have a little airflow under the floor. CAT6 and power do dissipate some heat. Also condensation may build up. The holes you cut for the cabling going into the racks while be mostly filled with cable and have little airflow. Just replace 2 tiles (1 on the cold side of the room, 1 on the warm side) with a grate. (Or cut a hole in a plate and place a grate over that hole.) Natural convection will do the rest.
  • You will have to bring in a proper electrical earth for the racks anyway. Attach it to the floor as well. Won't cost you any extra and it certainly can't hurt.
  • This is more of a general piece of advice when dealing with AC units. If they use a liquid coolant install a fluid detector/alarm under the floor. A coolant leak (in the AC unit itself or in the plumbing going to the condensers outside) may go undetected for a while as long as cooling capacity isn't overly affected. But you don't want the coolant to pool under the floor. Bear in mind that chemicals in the coolant have a nasty tendency to dissolve plastic shielding around your cables !
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Good points, thanks. I've got an APC environment monitor with a leak detector on. The airflow could well be an issue since the breeze block wall goes under the floor and even the cable entry points are fire-breaked. –  SmallClanger Oct 2 '12 at 20:05
    
They should be fire-sealed. An other reason why I mentioned the under-floor airflow as I have seen a number of server-rooms with mold and even a few mushrooms under the floor. Warmth, a little bit of moisture, dust and a few spores is all it takes. When there is some airflow at least the AC can keep drying the air. –  Tonny Oct 2 '12 at 20:28
1  
Oh, I'm not doubting the fire sealing, just pointing out that you're right that there's no other points of airflow beyond the rack entry points, which will be pretty thick with cables. Much as I'm quite taken with the idea of starting a mushroom farm on the side, I think some ventilation will be a good thing. :) –  SmallClanger Oct 3 '12 at 9:32

That floor system sounds very similar to what we had at a previous job, and over the raised floor panels we had identically-sized ESD carpet tiles. I have no idea what brand any of it was, but a quick google for ESD carpet tiles gave me this, for one

The carpet tiles we had were fairly thick and heavy (7 or 8mm thick, I'd guess) and were glued to the floor panels, but the glue wasn't too strong and they were easy to pull up when we needed to. We never re-applied any glue to hold them back down, they were heavy enough to just sit there.

The only picture I can find is this blast from the past (Man, I loved those MicroVAXes and that AlphaServer 2100 4/275!):

enter image description here

Looking at the picture, I remember that the carpet tiles were offset from the floor panels. We dragged things over the carpet all the time and the tiles never pulled loose or suffered any damage.

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I'd not considered carpet. I'm not keen on it now, partly because I don't trust the contractors to get the right stuff (since it was they that bought the wrong vinyl in) and I've had static problems before on tiles I was assured were "ESD safe". (Good photo, btw. I'm certain that other Vax is called 'Ernie'.) –  SmallClanger Oct 2 '12 at 20:01
    
I wonder if the box in the right-hand side of the picture is Big Bird ? –  Tonny Oct 2 '12 at 20:31
    
No, the AlphaServer to the left of Bert and Ernie was BigBird, and the HP 9000 tower on the desk that ran the financial system was called TheCount. –  Ward Oct 2 '12 at 20:40
    
The ESD capabilities of the tiles were never really tested, since even with the A/C running, it never got very dry in the room (one good point about Vancouver's rainy weather). –  Ward Oct 2 '12 at 20:42
    
@Ward I recognized the Alpha. Been a while since I encountered those in the wild. I still must have an Alpha workstation somewhere in the attic, but I haven't used it for at least 15 years. Would probably take an archeological dig to get it out :-) –  Tonny Oct 2 '12 at 21:06

First of all, I know this is an old thread. But I've always been of the mindset to reply to threads despite their age, because they are always a good source of information for future visitors!

Regarding the OP's question about woodcore panels, there are still a couple suppliers out there but trust me, woodcore access floor panels are NOT used hardly ever. Yes, they have worked in the past but most people are shocked you would introduce a combustible material into your data center.

Regarding the 4" "void", that would be referring to the height of the raised floor. 4" is really in the realm of "low profile floor" which are usually 6" and less. They are for power and data cables, not for air.

Ask any HVAC engineer about underfloor airflow, and you will get a lot of opinions, but no one would recommend pumping cold air into a 4" floor. It just won't work, and it will cause far too many problems (hot spots, etc.) than it's worth.

If you want underfloor airflow, the minimum height is really 24". I've seen far too many 12" floors with huge airflow problems. It's just not doable. Please don't try to pump any air into such a short floor! The cables will not give off enough heat to require cooling!

If you are interested in low profile access floors, I would suggest either Netfloor USA Or Freeaxez floors. Once you get above 6"-8", you are talking regular access floors and your brand choices open up considerably. With either of those floors, though, you can put lots of different floor coverings on top (carpet, tile, etc.) or just leave the panels bare.

Bottom line though, I would steer away from wood core panels. They are hard to find and are a smoke and flammability issue. Also, I've found they do tend to chip more.

Also, regarding optimum floor height, everyone will have their own opinions. But I can tell you from first hand experience, that the big boys who are using raised floor in some of their data centers are building 4'-6' floors. I'm talking Google, Apple, etc.

Not ALL of their server space has raised floor. A lot of it doesn't. They do overhead cabling and duct in the cold air, so no need for the floor. But when they do have floor, it's plenty tall to allow for cables, piping and unrestricted airflow.

I hope this helps!

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