Okay, our datacenter doesn't charge us based on our "useage" just on how many Amps we have delivered to our rack. I'm planning on putting in a new rack this upcoming year for some server expansion, based on This article. Each server has a crapload of drives, and in turn, uses a crapload of power.
This rack will include.
1 Cisco Router.
1 Fiber Switch
1 1U Storage Controller, standard Dell 850 server.
11 3U Storage Servers, each with dual 750-watt power supplies.
So… I'm trying to calculate how many amps i should theoretically need. I dont have an example server yet to see just how much a 3U – 45-drive server pulls. So i figure it needs two power supplies, so lets go with 1000 watts of pull. Plenty for the hard drives, plenty for the onboard stuff. 11 x 1000 watts is obviously 11000 watts of power.
A=W/V.
W= 11000.
V= 120v.
A= 91.
This is where my brain kinda tripped out. 91 amps of power is sheer insanity. (the most i've had piped to a rack atm is 40, and its only sitting at 60% capacity.
And thats with only 1000w used per server — if the PSU is pulling full current at 1500watts for the system, thats something to the tune of 140amps.
…. This sound right or i'm I just crazy? Surely i did something wrong, 140amps of power is insanity.
****Edit: Box is actually 4U, so numbers are different then displayed here, but not by much.
Best Answer
Your figures sound like they're on the right track in general, a dual disk, dual processor box like a HP DL380 pulls about 350-450w on average so add in 43 x 15-20w for the disk and you're not far off a Kw per chassis. This gives you two problems, you're going to need 4 x 32A PDUs to support dual PSUs and you've got a reasonable amount of heat coming from the rear if the rack that needs scrubbing. I also suspect that your hosting company might bitch about this and insist on you splitting your kit between 2 or more racks instead.
That said I can't think of any other way of getting that amount of disks into that density, what make/model are the 3U boxes by the way?
Edit - have you done the weight calculation yet? You should run that by them too, that sucker's going to be quite heavy.