Ok, ive been trying to find this out for some time now and asked alot of people and gotten alot of conflicting results. So hopefully some of you will be able to help me out. I am wandering how many Athlon XP/Celeron servers I will be able to put in a 42U cabinet with 15amps of power (12 amps since of the 80% breaker on all 15 amp circuts in the US). Some people have told me that you would only be able to put 12. Others have said that you could fill the whole 42U cabinet up. I am very confused because I dont understand why you would have a 42U cabinet that in reality could only hold 12 servers due to power usage. PLEASE SOMEONE HELP ME OUT!! How many servers will I be able to fit on the 15amp circuit??? Also what is a reasonable price to pay for 15amps of power?

depending on what else you have in the boxes, i would say 12-15 would be a safe bet if you use a pdu/rrp that powers equipment on sequentially after power loss. machines draw the most when they first power on, so having them all power on at the same time is a BAD IDEA (tm), while powering them all on sequentially will work fine since they will draw less power after boot. you *can* fill a full 42U cabinet, but you are going to have to use 4U chassis =] there is no way you can put 42 machines on a 15 amp circuit.

15 amp or 20 amp circuits in cabs are an industry standard. the major reason would be that most datacenters are not equipped to cool racks with a higher power consumtion than that (most are set up to cool 1-3kW per rack, which is ~ 10-25 amps). while this is most certainly frustrating, there is not much you can do. as a consolation, you may be able to rent the remainder of a cabinet as a studio apartment to a midget =]

reasonable is in the eye of the beholder. likewise, all power is not created equal. i would pay more for redundant conditioned power than i would for a circuit from a local power company directly. some markets are more expensive for power than others, notably new york city is insanely priced.

paul

When the industry adapt the standard, they have not anticipated that the rack would be used to pack 1U servers. They were designed to hold Telco gear which consume next to nothing in power.

Consider doing 2U to pack the cabinet if you dont' like to see space wasted. That would save you some initial capital on the casing.

calcsRcool - I would say about $200-$250 for an extra 15Amp circuit would be usual market cost.

CW charges $550 for an extra 20 AMP

Originally posted by Mrdredd
calcsRcool - I would say about $200-$250 for an extra 15Amp circuit would be usual market cost.

good luck getting that pricing in most markets. dont forget the install fees =]

paul

Sorry to 'hijack' this thread, but I'm looking for data center space & didn't realise power might be an issue until I read this thread.

One data center I've approached list their default feed at 1KVA, what would this equate to in amps?

Thanks

Originally posted by Cloudmaster
Sorry to 'hijack' this thread, but I'm looking for data center space & didn't realise power might be an issue until I read this thread.

One data center I've approached list their default feed at 1KVA, what would this equate to in amps?

Thanks


Im pretty sure 1KVA = 10 amps...

I would say about 12 servers max, just for market comparison we charge $350 for 20 amps of power over the first 20 in the cab.

Power varies a lot by region. In Dallas we dont pay the power companies as much as other regions per kw/h. We also dont pay the same rates as others for our labor costs for electricians. $160 monthly with $150 NRC is our rate at Colo4-Dallas. When I looked at going into NYC that rate would not work.

If you havent signed for the cabinet yet try to get some more power. Some dont charge an install if all the have to do is increase the breaker size. Your problem is that best case scenario you are close to maxed out. What if you grow or usage on the servers goes up.

I have a cabinet currently at about 30U utilization, all of which are 1U except for one minitower. The circuit is currently reading under 6A.

29U at 6As, they must be Cobalts or similar. Most 1U servers use around or just under 1 AMP

so much conflicting results!!! see this is what im talking about some people say that you can fill the whole thing others say oh no you can only put like 12-15!!

the large difference is that people who say they can fill it use small boxes that dont do any work.

paul

It all depends what you're puttin gin the boxes, faster drives use more power e.g. 10k SCSI. We've got some Dual Tualatin boxes, with 3GB RAM, 6 x 10k RPM SCSI drives and an IDE and they draw around 1amp on their own, we've got other boxes, same sort of spec but with 2 x SCSI and an IDE and they draw around 0.6amp so it all depends what you're going to put in the boxes.

Originally posted by calcsRcool
so much conflicting results!!! see this is what im talking about some people say that you can fill the whole thing others say oh no you can only put like 12-15!!

Don't be confused. Buy a clamp meter from Fluke - http://www.fluke.com/products/home.asp?SID=5&AGID=3&PID=30405 and see your power draw for yourself.

TP

Also just remember the calculation they taught you in school (hope you where listening), and that is the Current x Voltage = Power in Watts. So you can then work out how much can fit by the size of each power supply in each server.

I'm a little lucky, My datacenter gave me 15Amps per 5U of space, I bought 126U of space with them giving me about 375Amps.

They sold me this VERY VERY cheap and relized it after my contract was signed. I'm a lucky man and can sell space a lot cheaper than my uplink can currently.... This is giving me TONS of business.

Originally posted by AusJeff
Also just remember the calculation they taught you in school (hope you where listening), and that is the Current x Voltage = Power in Watts. So you can then work out how much can fit by the size of each power supply in each server.

this is incorrect. although i may have a 350W psu, if im running a single p4 with one hard drive off of it, it isnt going to use anywhere near that. the rating for the power supply is a rating only - your stuff can, if it needs to, pull the full 350 - it doesnt have to.

paul

So you can then work out how much can fit by the size of each power supply in each server.

Umm.. Power supplys are VERY over rated. This really won't tell you squat. Just because you have a 400Watt PSU, that does not mean it actually _uses_ 400W

From what I've experienced, $200-$250 should buy you a 20amp circuit. I can't even buy a 15? *shrug* But a lot of facilitys are very expencive for power, and odds are they earn it with the right equipment in place. I charge $250 per 20A circuit when I sell our racks.

If you got a dozen servers on that circuit, I would think your doing well. But, definatly have power readings checked often when adding machines. You can't fluke a line unless you can seperate the hot wire, so odd's are you will have to have the datacenter assistance. There are sooo many variables with equipment types and components, you have to measure and see.

Also, you can squeeze a tad over 80%, if your willing to risk a trip ;)

Just for comparison, I've got a 45U cab with 4 X 20 A circuits - 40 Dell 1750 dual Xeon servers draw plenty of juice. (but also push plenty of bandwidth)

Rack + power = $2400 per month!

thats pretty cheap sjhwilkes for 80amps and the rack, I actually pay $10 more for 80amps and a 40u rack

Wow. I guess power is cheap in Denver. We pay well under $200/mo per 20AMP curcuit. :)

It all depends what you're puttin gin the boxes, faster drives use more power e.g. 10k SCSI. We've got some Dual Tualatin boxes, with 3GB RAM, 6 x 10k RPM SCSI drives and an IDE and they draw around 1amp on their own, we've got other boxes, same sort of spec but with 2 x SCSI and an IDE and they draw around 0.6amp so it all depends what you're going to put in the boxes.

It's important to note that this will be at 240V not 110V/whatever. It does make a difference ;)

exactly. watt = volt * amp. this may seem inconsequential to you, but very important to the datacenter, since they pay per metered kW and the cooling is planned based on kW as well.

paul

Yeah, sorry, didn't think at the time (I usually post on majority UK forums). However it still applies that what you put in the box can make a big difference, especially when you've got a rack full.

Originally posted by rusko
this is incorrect. although i may have a 350W psu, if im running a single p4 with one hard drive off of it, it isnt going to use anywhere near that. the rating for the power supply is a rating only - your stuff can, if it needs to, pull the full 350 - it doesnt have to.

paul

True, but knowing what's in the box is a good start at roughly knowing what it needs to draw. But if you have remote reboot ports, most of them will tell you the current load levels.

Jeff.

Originally posted by AusJeff
True, but knowing what's in the box is a good start at roughly knowing what it needs to draw. But if you have remote reboot ports, most of them will tell you the current load levels.

Jeff.

yes, *whats in the box*, not the rating of the psu. rrps are usually off quite a bit on the readings ime.

paul

Originally posted by rusko
exactly. watt = volt * amp. this may seem inconsequential to you, but very important to the datacenter, since they pay per metered kW and the cooling is planned based on kW as well.

paul

Plus people forget that for ever AMP it takes to power the DC, it usually takes another AMP to cool it. So DCs are not just charging for power that goes directly to the server. I have seen people do all the math and complain why they pay so much for power, but it is usally because they forget about cooling.

exactly. most dcs are cooled ambiently, in which case it does take an amp or so to cool it. if you do local ducting (suck, push or both) you can get it down to about 1/2. i havent seen that done too often outside facilities that do bainframes or blades though.

paul

Actually alot of the older DC are not cool correctly, the reason being is they haven't plan on the power density of the 1U servers. Packing 40 1U servers in a rack is alot alot of heat, if you start seeing servers randomly rebooted, it maybe time to look at installing fans in your cabinet.

Originally posted by UmBillyCord
Plus people forget that for ever AMP it takes to power the DC, it usually takes another AMP to cool it. So DCs are not just charging for power that goes directly to the server. I have seen people do all the math and complain why they pay so much for power, but it is usally because they forget about cooling.

Where?? Maybe in Texas but in the bay area where most of the datacenters are its cool year around, about 60-65 in the summer and about 45-55 in the winter. As for dense cabinets full of 1u servers, you don't need to air condition that you need fans to blow the hot air out and bring the regular air back in, and fans hardly take any electricity.

The heat is not coming from outside the data center. 1U servers are great generators of heat. All those little electrons zooming around your CPU heat your server up like it's a damn oven. Not to mention heat from the power supply, hard drives, NIC, memory ...

If you have ever stood behind an entire rack of 1Us, you know what I'm talking about. Even if the data center is "cool", you will still feel all the heat that the servers are giving off.

hence the use of a fan... moving the hot air out and regular air back in.... fans can also be used to exchange not only cabinet air with datacenter air but datacenter air with outside air....

Originally posted by calcsRcool
Where?? Maybe in Texas but in the bay area where most of the datacenters are its cool year around, about 60-65 in the summer and about 45-55 in the winter. As for dense cabinets full of 1u servers, you don't need to air condition that you need fans to blow the hot air out and bring the regular air back in, and fans hardly take any electricity.

As pointed out by Jay, it has nothing to do with what you posted.

hence the use of a fan... moving the hot air out and regular air back in.... fans can also be used to exchange not only cabinet air with datacenter air but datacenter air with outside air....

Why would you blow outside air into a DC? I would never use such a DC that is too cheap to properly cool by running redundant condensers and at least double redundant AC units. I have been in a DC with a broken AC unit. Swamp coolers wouldn't even cool the place.