Fundamentals of Data Center Power: Power Calculations

hi this Dave Cole I'll be instructor for power calculations module as we continue talking about power in the data center we're gonna look at some power calculations if you have any questions as we're going through this module please be sure to use the question comment box and happy to get right back with you with answers to your questions so let's get started let's look at the topics that we're going to cover in this module we'll look at calculating power requirements so in the data center if I'm building a new data center or if I'm adding on to a data center how much power do I need to be able to power all the equipment that I'm gonna put into that data center and we're gonna look at power consumption in the data center where's my power going in the data center I know I'm consuming it but what is it that's that's using up the power so look at pop calculating the power requirements it's pretty straightforward but it is complicated a little bit by how much redundancy am I going to have and calculation of future load it's important that we're as accurate as possible when we're calculating power requirements if we underestimate power requirements we may have some future power disruptions we never want to get caught without enough power or cooling or space on the other hand if we overestimate power requirements we're gonna run into excessive initial cost and we're gonna have a higher ongoing maintenance cost because our energy efficiency is not going to be very good right so the more accurate we can be the better chance we're going to have of being reliable and available in our data center and also operating energy efficiently where's our power going in the data center as much as half of it can go to cooling alright so we talked about a little bit about cooling and we're gonna talk quite a bit more about cooling and ways we can be more efficient but cooling is often half of the power in the data center and we have our critical loads which can be you know a third or maybe closer to a half on that and we also have UPS and efficiency when we're charging our UPS batteries that can be quite a bit of our of our overall power usage and then lighting in the data center we don't think too much about lighting but it's out there right so we would like to be as efficient as we can in all of these areas so let's go through an example of what a typical data center design company would use to calculate what your power is going to be in the data center so we have to start with some assumptions let's assume we're gonna have a 5,000 square-foot data center but 150 racks in there and half of our cooling is going to be direct expansion and half of its gonna be chilled water we don't need to worry too much right now if we're not sure what direct expansion cooling is or chilled water but it's important to know that there is a difference in in cost for different types of cooling strategies so first thing we're gonna do we're going to start by determining the size of our critical load what's in our critical load things like servers and routers storage devices telecommunications equipment security fire monitoring right all of these things are critical oh these are all the things that we want to make sure are going to be up all the time right we're making a list of all of these devices we're gonna look at what their power rating is we can look at nameplate values but ideally we're gonna use the manufacturer calculators and figure out how much power we think these devices are really going to draw so we're gonna look at the power rating voltage requirements do we need single or three-phase right we need to know all of this stuff ahead of time because we're really trying to design a power system to match the equipment that we have so let's put this together in a little grid and ideally we want to do this at a rack by rack basis because if we've got kind of a standard rack and we can and spend a little bit of time with that rack figuring out how much power it's gonna draw and if we then say most of our racks are going to be the same it now makes our calculations much easier so just for purposes of example let's say we're gonna have a couple of servers and there's our power ratings and a couple of storage arrays so we're gonna say total at this Rack we think it's gonna be one and a half kilowatts of power now knowing that we're going to put a hundred and fifty racks in here I can take one-and-a-half kilowatts Iraq multiply that time in 150 racks and we're at 225 kilowatts well that was pretty easy except we're not there yet right because this is only our critical load we've got to worry about our infrastructure and cooling and lighting and everything else it's a good start we've gotten somewhere so let's take our critical load and now we need to figure out how big are we gonna get our datacenter is undoubtedly gonna grow over time so what do we think our future loads gonna be again we don't want to get caught without power so let's try to to give ourselves a little bit of leeway here so let's figure about 20% growth so that's another 45 kilowatts right 20% of our 225 another 45 kilowatts so now we're up to 270 kilowatts sometimes in the year we're going to max out our data center let's imagine an amazon.com the day after Thanksgiving as we get into holiday season people start buying gifts maybe all their servers are really cranking or maybe it's an accounting firm you know on right before taxes are due or whatever your business model happens to be there's gonna be some times when you're drawing a lot of additional power we're gonna call that a peak power multiplier and what we're going to do is give ourselves a 5% overhead for when everything's cranking at the same time so now we take our 270 kilowatts can multiply that by 1.05 our peak power multiplier and that's going to give us an extra 13 and a half kilowatts of power that we need to account for okay so now we've got a critical load now we want to figure out what's our UPS load this is where we start looking at things like UPS efficiency okay let's assume our UPS efficiency is 88% which means if I put a hundred kilowatts in eighty eight kilowatts come back out right so I'm going to lose some of my power inside the UPS I need to account for that because that's going to be a big number for us I also need to remember that my UPS is going to try to take care of itself so if its batteries aren't charged as much as 20% of the power going into the UPS is going to be used to charge the battery so I have 12% inefficiency I have 20% battery charging than I need to worry about that's 32% 32% of my critical load is eighty six and a half kilowatts I need to account for that when I'm looking at my total power and in normal conditions with a charged battery my charging load is negligible but if it's completely discharged or partially discharged again 20% of that could go to charging the battery now let's look at lighting for lighting purposes we're gonna estimate about two watts per square foot we have five thousand-square-foot two watts per square foot that's ten kilowatts for our lighting load now we start adding all of these up so we started with our critical load our server and IT equipment routers and things like that that was 225 kilowatts we put in 20% for our future load we added a peak power adjustment we added our ups and battery overhead we added lighting and now we're up to 380 kilowatts right so our load starting to grow we need to account for all of that now I need to add in cooling and I said for purposes of this example half of my cooling could be done with chilled water so I'm gonna cool 190 kilowatts with chilled water chilled water is pretty efficient so it's gonna take me about 0.7 of that is how much power it's gonna draw so I take point seven times 190 and I get 133 kilowatts direct expansion not quite as efficient so I'm going to take for me to cool 190 kilowatts it's going to take me at another 190 kilowatts to cool that so now my cooling load I add those two together and I get 323 kilowatts now our numbers trying to get pretty big remember we started way back one with just 225 kilowatts for a critical load but we've added future load peak power draw ups and battery and efficiency lighting and now we're gonna add in this big chunk for cooling and all sudden we're looking at this at 703 kilowatts right these are pretty conservative numbers that we use but again I don't want to get caught without space power and cooling those are big important things for me now how much do I need to tell the utility company how much power do they need to give me well I can't tell them 703 kilowatts even though I think that's what my total power is I don't ever want to use more than 80% of what they give me all right I want to have that 20% overhead according to the National Electric Code so I need to take my total power my 703 kilowatts multiply that by another 25% so I need to tell the utility company hey mister utility company I need 879 kilowatts right so way back with our 225 kilowatts all sudden you know a number almost three or four times that is what I have to tell the utility company again pretty conservative numbers but this is the process that we would go through to calculate power in a data center so here it is all kind of laid out for you now I want to look at how big a generator do I need I look at my generator in two different stages one for my critical load and one for my cooling load because I may or may not want to run my cooling off my generator I have pretty low density data center in this case I may not need my cooling to be run off generator so we split these out plus the calculations are a little bit different for cooling versus my critical loads so I take my total power load 380 kilowatts I multiply that by 1.3 to get how big a generator how much generator I need to to supply power for that much load for cooling I have to multiply that number by 1.5 5 because we got mechanical gear we've got pumps and motors and things like that on cooling it's harder for a generator to supply that power so if I add those up I get almost I get 995 kilowatts is the size of the generator that would be required if I want to support both my IT equipment my cooling so again these numbers add up very very quickly people forget about things like UPS charging and they forget about things like lighting and future loads and things like that but these numbers can can grow very very quickly where's my power going in the data center ideally all my power to the data center would go to my IT load right that's them that's the important stuff my servers my storage my telecommunications equipment unfortunately all the power going in the data center doesn't go to my IT load some of it gets sidetracked some of its going to go to my support infrastructure my cooling and lights and security and things like that right and part of its gonna go to my UPS my PDU cabling and switches and I'm gonna have power losses any time I run power over a cable I lose some of that power every time I run power through a UPS I lose some of that power every time I go through a PDU transformer I lose some of that power so I had these losses in the power system the remaining power now is what goes to my IT load right so certainly not all the power maybe only half the power maybe only 1/3 of my power is now going to my IT load so we have a metric and energy efficiency metric in the data center called PE power usage effectiveness and what this value is is the total power to my data center all right everything going to my data center divided by how much of that power actually gets to the IT load we would like that number to be one that's as low as it could get that would mean that every bit of power going to the data center is going to my IT load all right typical data center is about two that means about half the power going to the data center actually makes it to my IT load because of the support infrastructure and these losses in the power system so let's look at this power consumption data center we we looked at this before but now we're going to break it into a little bit more detail so we've got power going to IT equipment you know maybe 30 maybe my computer and air conditioner my cracking it maybe that's taken nine percent uh humidifier may take some my chiller may take some my UPF my PDU my lighting all right so a lot of different entities want to grab some of my power and the reason I break this up and your mileage is certainly going to vary in your data center but the reason I bring this up is if I want to improve my energy efficiency in the data center I'm probably not going to start with lighting because that's only one percent of my total load I want to look at the big areas I want to look at IT equipment and my crack unit and my chiller and my UPS because those are taking bigger chunks of my power consumption in the data center so it's kind of a recap we talked about where was the power going in the data center and certainly a lot of that power is gonna be wasted we're gonna talk and future modules about some other modules about how we can reduce some of that wasted power in the data center we talked about how we can calculate in a new data center or an expansion of a data center how much power we're going to need if you have any questions about that please feel free to use the question comment box we'll be happy to get back to you as soon as we can with any questions on that the meantime thank you very much for joining us in this module and look forward to having you in other modules as we move forward

Channel: GogoTraining

Views: 37,089

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Keywords: video, tutorial, course, training, self-paced, online, on-demand certified, Data Center, Data Center Power, Power Requirements, Power Consumption

Id: 1mTLJzPOSI0

Length: 14min 53sec (893 seconds)

Published: Fri Sep 21 2018