New Data Center Standard

mstansberry writes to tell us that the Telecommunications Industry Association (the people who brought you the CAT standards for unshielded twisted pair cabling) recently published a 148 page document meant to standardize the design considerations for every single aspect of a data center. The standard covers everything from site selection to rack mounting methods.

Comments

twisting

[seanadams.com]

Speaking of CAT standards, has anyone else had a good look at the differences between CAT3, CAT5, etc?

CAT5 just seems to be twisted a little tighter, but CAT6 actually modifies the twist gradually, in a cycle that repeats every few feet, with each pair 90 degrees "out of phase" from the next. Plus theres (sometimes) a plastic "spine" in there to maintain spacing and/or bend radius. It's not obvious to me how varying the twists-per-foot along the cable should help - anyone know?

Re:twisting

[Mr. Flibble]

because of the extra twisting there is less crosstalk. The less crosstalk, the more information you can pump down the wire, thus the difference between Cat 3,5 and 6.

(FYI, crosstalk is interference from a parralell channel in the wire)

Re:twisting

[rusty0101]

Not sure entirely myself, however as a thought, having a constant twist (different from one pair to the next, but the same for the length of the cable) could set up a situation where two cables are in phase at several points alog the cable run, and some signal transfer may hapen.

Varying the twist rate along the run of a pair, as well as doing what you can to keep it out of phase with other pairs by braiding, or other means would make it possible to set up a longer cable run without viable phase transfer points that could cause signal bleed between pairs.

However that's just conjecture on my part. I am sure someone will come along who can give us the math to show that my conjecture is entirely wrong.

-Rusty

Re:twisting

[SoloFlyer2]

Varying the twist rate only helps when u have several cables together ( Think 4 or 5 cables in a conduit ). Basically it just reduces the chance that 2 cables next to each other are going to have exactly the same twist rate.

In other words it reduces cross-talk between cables :)

Re:twisting

[DaEMoN128]

I am BICC certified. There is a difference between CAT3 and CAT 5. The twists are much more pronounced on CAT 5. It may not look like it, but there is a big differnece. There is also different amounts of twists per pair. CAT 6 is something I havent had much hands on with (we use mostly fiber for that stuff). CAT 3 has much lower frequency response per pair than CAT 5. A good cable tester can actually verify that for me if you can get your hands on one (see network analyser). Just from looking online, CAT 6 has a minimum 250MHz bandwith while CAT 5 has a minimum 100 MHz bandwith per pair. http://www.lanshack.com/cat5e-tutorial.asp check here. It says CAT 5e is the same as CAT 6 but CAT 6 is manufactured to a higher standard. I guess that the fab tolerances are tighter for Cat 6.

Doomed to failure?

[Toby The Economist]

Be interesting to see if it's useful.

When you specify something like a cable, it's straightfoward to get it right, because the job the cable does and the way it's used is very well understood and doesn't vary between users.

With something complex like a data center, there's so much variance in how they're operated, exactly what they do, where they are, etc...having a standard may well *not* fit everyone's needs, either because their needs were not perceived or understood at the time or because their needs simply cannot be met by the standard.

--
Toby

Re:Doomed to failure?

[JanneM]

With something complex like a data center, there's so much variance in how they're operated, exactly what they do, where they are, etc...having a standard may well *not* fit everyone's needs, either because their needs were not perceived or understood at the time or because their needs simply cannot be met by the standard.

True.

But when you have a formal standard, you have something to measure against. Every aspect of the data center design is not only standardized, but the how's, why's and therefore's are spelled out. If you suspect the standard doesn't meet your needs in some respect (a clear lack of surround sound for late-night fps tournaments, say), it makes it clear exactly how your criteria changes the requirements, and it makes it much easier to see how it could impact the rest of the design.

So even if you use not one single recommendation (we need the disco ball, damnit!), you have something reasonable and well documented to compare against, which makes your job easier.

Pity it's $250 for a peek

[darnok]

I'm curious to see what this document contains: whether it's an ITIL-like view of the world (e.g. a data centre runs on change management, capacity management, problem management, ...), a hardware based view (e.g. a data centre needs a raised floor to duct cables, air conditioning, secure access, racks, ...) or something else.

Just not curious enough to pay the price to find out

Steal the F*ing Manual

[fyoder]

Just not curious enough to pay the price to find out

Seriously. If all manuals were that expensive there would have been no 'RTFM'. It would have been 'STFM'.

Re:Hum?

[Samari711]

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Re:Not this again ...

[drsmithy]

I don't imagine this would be an especially effective means of encouraging compliance either... "we'll tell you what to do for the low, low price of $250!!"

Out of the costs involved in setting up a data centre, $250 wouldn't even qualify as a rounding error.

Alternatives to THIS book

[xmundt]

Greetings and Salutations.
          Interestingly enough, a quick google search for "data center design" comes up with more hits than one can shake a stick at, ranging from free to fairly inexpensive (under $100.00). I have to admit that I wonder if THIS magnum opus has anything in it that these OTHER resources do not cover.

          It never ceases to amaze me at the number of books out there that are supposed to be useful learning tools that are nothing more than a slightly changed rehash of the man pages for a given program.

          Regards
          Dave Mundt

This is a really bad idea, sort of

[DaEMoN128]

From TFA, this is a "checklist" for CIO's. Last thing I need is my PHB having a list to check off and thinking they are requirements instead of suggestions. You never give a PHB this much info. They dont know what you are doing a good part of the time anyways... and a little info is more dangerous than none.

It can be a good idea if the techs get a hold of it though and stop giving my 2 inches of slack on these fiber runs and give be a proper service loop with good cable dressing instead of the rats nests I've had to fix recently.

Re:Raised Floors?

[marquis-cablewitch]

But without raised floors where am I supposed to hide the bodies?