Datacenter power terminology and requirements explanation?

Discussion in 'OT Technology' started by korrupshun, Apr 7, 2008.

  1. korrupshun

    korrupshun New Member

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    heres the quick explanation....at my old job i handled the switches and routing and another guy handled all the physical requirements (ordering racks, power distribution, etc.)....well i just accepted a job as a datacenter manager and have been tasked with making the power solution more efficient....

    at the risk of sounding like a complete moron, i have heard terms like 220 but have no real baring on how many or what type of equipment that can provide power for...ive been googling for the past 2 hours but am finding nothing (perhaps im searching for the wrong kinds of things)

    can anyone give me a basic rundown (or hell a good google search to help me out) of what exactly the typical power requirements are, and what the terminology surrounding it would be? at my old job i was told it was rather simplistic, i just never took the time to get the details and now i need them heh
     
  2. DAN513

    DAN513 OT Supporter

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    what type of systems are you running, how many, any external peripherals?
     
  3. korrupshun

    korrupshun New Member

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    well thats a toughy....there no real consistency....theres a 6509, 4500, and a foundry edge device...the rest are servers (ranging from some really old ass 1Us to one brand new blade server) and a crap ton of devices i have never seen before (industry specific)....

    what i need is quick explanation of what typical power requirements are (a few basic examples of how, where, and why they apply) and explanations of what 220 or 110 are and how they are used...and anything beyond that which may be useful....

    i just need enough to build google searches around unless i can get an explanation that i feel is more than enough for later this coming week

    EDIT: im still inventorying the datacenter so those are my best guesses, i do not know exact number of devices...kinda why i need the general understanding/knowledge
     
  4. korrupshun

    korrupshun New Member

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  5. deusexaethera

    deusexaethera OT Supporter

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    Oh god, man, that's a tall order. It might sound like a cheap shot suggesting Electricity for Dummies, but that's probably your best option to learn what the terminology means in a short period of time.

    Also worthwhile is searching "alternating current" and "three phase power" on www.howstuffworks.com. (Any time you see a plug with 4 prongs, it's three-phase power, and it's a whole lot more complicated than plain-old AC.)
     
  6. korrupshun

    korrupshun New Member

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    hrm....didnt seem like the datacenter needs were all that complicated when all i here is 'we need this many 220s'....but perhaps thats why i can't find anything that explains the power end of thing
     
  7. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Well if the 220 is a voltage reference, then it is what it is.
    220 volt line.
    But I can't imagine any computer gear being powered by that with a possible exception of maybe a UPS.

    I mean, there's no way that they're talking about model numbers?

    :confused:
     
  8. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    The only time you need 220's is for UPS - I can't think of a stand-alone server that would need 220. So in our rack for example, I went to APC's site and tried to find out what kind of UPS I needed for our rack, and lo and behold, I need a 220 circuit, hard wired in no less.

    But a less power hungry solution doesn't exist until you dive into virtual servers.
     
  9. deusexaethera

    deusexaethera OT Supporter

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    We have a 5000VA UPS that uses a twist-lock 220-volt plug. Lucky us, we already had one.

    Make sure you have one of those for each rack. And don't worry about whether your building has 220-volt power, because they all do.

    As for virtual machines being less power hungry, that's true, but only in terms of amperage -- you still need 220V to run the backup batteries to keep those servers alive if the power goes out. (You can get backup batteries that run on 110V, but to be honest, you should really get 220V units just because of the twist-lock plugs -- much more secure that way.)

    - - -

    As for the 5000VA UPS I mentioned, you should know that VA != watts. The US standard for measuring wattage requires that the voltage be averaged out across the entire alternating-current sinewave, which means the voltage used for calculating wattage is roughtly 2/3 of the peak voltage at the top of the sinewave. VA, on the other hand, uses the peak voltage instead of average voltage, presumably because peak voltage equal peak stress, and they're trying to demonstrate the maximum stress the unit can withstand -- but in all reality the appeal of using VA instead of watts is VA lets them legally slap a bigger number on the box.
     
  10. dissonance

    dissonance reset OT Supporter

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    I always preferred Legos over Building Blocks because the structures I made were much more secure....




















    Is that really the only reason to use a 220 (I'm curious about your answer now)?
     
  11. deusexaethera

    deusexaethera OT Supporter

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    It's not the only reason to use a 220V UPS; if you're running a lot of servers off one UPS, you'll need more wattage than a 110V circuit can provide, which is where having double the voltage comes in handy. (The UPS will handle transforming the 220V power into 110V power for your servers, don't worry about that.)

    The twist-lock plug is just the reason why you should use a 220V UPS even if you don't need the extra power.

    EDIT: Also, because 220V circuits in the USA are three-phase power, the voltage is constant and doesn't oscillate up and down like two-phase AC power does, which makes it easier for the UPS to provide its maximum rated power reliably.
     
  12. deusexaethera

    deusexaethera OT Supporter

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  13. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    The twist lock has nothing to do with phases or power. Twist locks are safer, but it has nothing to do with 120 or 240 (or 208). You use 240 when you need to, that's all. Our rack would not work off of a single phase 120 drop since we drive everything off of one UPS.
     
  14. deusexaethera

    deusexaethera OT Supporter

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    So do we. And you're right that twist-lock connectors are optional, but theyre a lot more prevalent on 220V equipment. I don't think I've ever even seen a 110V twist-lock connector except on Wikipedia, whereas the only place I've ever seen a 220V non-twist-lock connector is on a clothes dryer.
     
  15. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    We use em all the time in lighting - and as you've alluded to, they're much safer and it's an added safety measure (although lighting instruments have an aircraft cable safety clip). Not to metion, it would seriously suck for the cable to disconnect 100 feet in the air. Doc would have had a much easier time in BTTF if he had used twist locks.

    On another note, it sure was funny watching my boss haul on this plug (we weren't going to be using it again) trying to unplug the unit, even after I said it was a twist-lock. I guess he didn't know what it meant :mamoru:
     
  16. korrupshun

    korrupshun New Member

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    awesome, thanks for all the replies...we're much closer to what i was looking for....i understand taht 220 is more than typically used for a single unit...we have multiple 220s that run down each row...so im curious exactly how many systems (types) i can connect to each before i start needing more juice (trying to be generic here cuz im still running inventory).

    for example, if i have a 48U rack of 1Us, how would i tell if a single 220 would suffice, or if i need more?

    also, the NEMA thing was good, i had forgotten about that term and remember there being half a dozen used in conjunction (comparison, needs/wants, etc.) so any other terms like that would be very useful
     
  17. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    Sigh.

    "been tasked with making the power solution more efficient...."

    Only two ways:

    1. Virtualization/Decrease number of servers
    2. Change servers to more energy efficient servers

    You can't make them more efficient by decreasing the number of feeds into the data centre. It takes X amount of juice to power a datacentre, you need to decrease that to make it more efficient. Decreasing or increasing feeds makes no difference (well until you pop a breaker which satisfies 1, albeit stupidly).
     
  18. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I knew it!

    :o
     
  19. deusexaethera

    deusexaethera OT Supporter

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    Look at the VA rating on the UPS, subtract a third, and add up the rated wattages of all the machines. If the machines are pulling more than about 3/4 of the UPS' capacity, add another UPS. (The extra 1/4 is for startup load; make sure you don't turn all the servers on at once.)
     
  20. deusexaethera

    deusexaethera OT Supporter

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    You assume the efficiency they seek is wattage efficiency, as opposed to wiring efficiency. Yes, you have to buy lower-wattage servers to decrease wattage, that's obvious, but it also helps if the back of the server room isn't an unbelievable clusterfuck of wiring too.
     
  21. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    There's no good reason to change the wiring for aesthetics.
     
  22. deusexaethera

    deusexaethera OT Supporter

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    Cleanliness is next to godliness.

    It's good when you can actually tell what's going to turn off if Circuit X blows a fuse.

    It's also good when you can unplug a cable from the back of one machine without having to weave a goddamned tapestry to get it completely out of the way.

    I'm getting the impression that you've never actually dealt with a messy server room before.

    EDIT: Oh, and if they have more UPS units than they need, then they're putting more load on the circuits than is necessary. So there's a bit of wattage efficiency for you.
     
  23. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    And I can safely say that you've never had someone above you and ask to make the power solution more efficient, because if you had, you would realize that bosses do not give a flying fuck about how much wire you need to untangle to make something happen.

    The most likely scenario is that someone got a hold of an article that describes how inefficient data centres are when it comes to power. Shit rolled down the hill and now it's in his hand to solve. If he takes your advice and spends time rewiring his servers this will happen:

    Him: "Well, I've done it. It's taken me a whole month, but the data centre is much more efficient"
    Boss: Trying to remember where this came from since it was a hot topic item a month ago, bluffs, and replies, "Excellent job. So how much did it cost?"
    Him: "Well I had an electrician and his apprentice redo all of the connections into the panel, so that was kind of pricey. But I think all in, it was only $20000"
    Boss: "Woah - that was a little more than I thought. So what's the ROI on that?"
    Him: "ROI?"
    Boss: "Return on investment. How long before the power savings of all of this work will pay for this expenditure"
    Him: "Wat"
     
  24. deusexaethera

    deusexaethera OT Supporter

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    Actually I was tasked to unfuck the rat's nest of cabling behind our server racks. The former division VP is an architect and he hates messes. (He quit after getting in one too many fights with the CEO.)

    I'm not saying he shouldn't stick to the "legitimate reason" of reducing power as the justification, but he should make sure the wiring is clean too. I did. And I did it on non-billed time, because it made my life easier to get it all done at once and then never have to worry about it again, like when we replaced 3/4 of our servers a year later.

    - - -

    Also, he can alway counter-bullshit the boss and give him a number he'll believe and will make him happy.
     
  25. korrupshun

    korrupshun New Member

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    you hit the nail on the head....the first task i was given was to un fuck the datacenters....its a NIGHTMARE....the power questions are centering around the fact taht they want to expand and are leaving that decision to me...

    the problem is, once i remove all the un used equipment, how do i know if i have enough 220s? if i need more, how do i determine how many more i need

    the questions i have, tho, are not quite solved since there are only a limited number of UPS...most of the equipment doesnt have or need fault tolerant power...so using UPS's as a measuring point will only work in a few locations and that will not be enough for me to accurately determine power needs

    how bout this, "if a quad core box needs _________(amount) power, then a 220 can handle __________ (number) boxes and here is why: _____"...i know this is a simple question, but im honestly a blank slate when it comes to power...and physics in college was a class i BARELY passed and the only reason i didnt get a 4.0 :(

    i have a brain block with this shit and need it spelled out at the basic level :(

    really its a pretty simple question, and think deus is startin to put me on the right path...giving me two points to look at and draw a comparison is a great first step...
     

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