Custom Server Power Distribution Supply

[goontron]

Re: Custom Server Power Distribution Supply

you really need a 2 or 3 channel hotswap psu with a spare plugin.

you cant be fucking around with systems you host for other people.

+1

i heard a story for an engineer from comcast i know, it goes like this: one time i was told about a switch with a duel redundant powersupply and one of the powersupplys had gone out and was sending a fault code down the lines to the main building, well the supply was never fixed and a some years later the second powersupply went out and about 15 city blocks were without cable and internet for a good three days because they couldn't get to the switch. why? because the four chunks of land that this switch was between got taken over and turned into a golf course, which was gated and shutdown for the winter. but the real kicker was that the owner of the gated golf course was on the switch that died, so they couldn't get ahold of the owner to open the gates!

[mariushm]

Re: Custom Server Power Distribution Supply

Reliability wise how would one of the Digikey adapters? Will it end up being more efficient long term? It says 87% which is fine. Will it last a long time? Because if I run multiple servers off one supply, if it goes out, I have a bunch of pissed off people.

I like your thinking though - I can end up spending about the same amount per server on a larger scale (more on CPU and mobo but less on case and PSU)

It's a Delta power supply... Delta, TDK etc do quality power supplies.
It's an industrial power supply, it's designed to be rugged and run at continuous output power for long periods of time.

The voltage on those power supplies won't go down with the load, they will be quite well regulated, within 2% of the value you set. If it says the lowest is 21.6v, then it's unlikely it will go under 21v.
Of course, if you want to you can open the power supply and make it go at lower voltage. In a lot of such power supplies, there's a resistor in series with that potentiometer, for example a 10kohm one, and the trimpot is 10-50k ... at the lowest value of the trimpot, the trimpot will be 0 ohm, so the total resistance will be that 10k that's in series with thetrimpot, so that sets the output to 21.6v or whatever's the lowest. If you desolder that and replace it with a 6.8kohm - 8.2kohm for example, you may be able to get even lower voltages.

You will have warranty on these, it fails, you return it to Digikey and in theory they give you another.

Any professional in any business like this will have hot spares, an extra power supply, extra ram, extra hard drives etc. If you don't plan to do that, you shouldn't do this in the first place.
Stuff fails, you have to be prepared for that, it's a cost of doing what you do...

[stj]

Re: Custom Server Power Distribution Supply

you really need a 2 or 3 channel hotswap psu with a spare plugin.

you cant be fucking around with systems you host for other people.

[shovenose]

Re: Custom Server Power Distribution Supply

Yeah, the thing is.. that eBay power supply is just a regular switching power supply.

Note that it says "for led strip light" - this refers to those strips of leds that have one current limiting resistor for every 3 leds, or something to that effect. So the strip itself does the current limiting, the strip is just a plain 12v load.

They're using the "led strip light" keywords as marketing, because people are noobs and search for led strip light power supply, they don't search for "industrial ac dc 12v power supply".

It's still a generic Meanwell (or some other chinese brand) 12v power supply, based on old half bridge or some other similar design, with poor power factor correction or poor efficiency.

You also have the idea that since the cpu is passively cooled, you don't need fans. False... the dc-dc converter inside the case and the heatsink on the cpu relies on cool air from outside the case to move through the case and cool itself. If you have a bunch of these in close proximity, there won't be any cool air outside and the systems will overheat. You'll still need some forced cooling to push cold air around those otherwise those cases will just screw with the cooling.

-

The more I think about it, the more I like that Asrock board with 19v DC input.
You could get some thicker aluminum sheets (maybe the size of mATX or ATX boards), drill some holes for some aluminum/steel spacers and screw the mb on that sheet of aluminum. Leave some space in front for 2 x 3.5" hard drives, that you can attach the same way, with some spacers. You made yourself a "blade server".

Now you can make a simple case out of some wood or other material, and simply have some channels on top and bottom spaced evenly. You can now slide the whole aluminum sheet in one of those channels.

At the end of the case, you only have the DC in jack and the network cable, and your blades will be nicely spaced so that you could screw on the end of the "case" a few 120mm fans to blow air through the blades, keeping the cpu heatsink cold and happy.

Here's something similar to what I imagine, only it's made of aluminum or steel and they 3d printed the plastic bits, you can just use some wood and drill holes into wood or aluminum : http://hackaday.com/2013/05/07/3d-pr...unting-system/

One of those 150$ Delta psus is rated for continuous 600w on 24v but it's rated for 1200w for 5s, so it will handle several blades booting up at same time.
It can be adjusted to 21.6v so 90% sure the motherboards will run straight from it.

In front of your case, you can bring a on/off switch for each blade (basically switch in series with the DC in connector). Optionally you could also put a 4-6A fuse in series with each blade (just in case a blade shorts out or dies in some way using more than 4-6 x 20v = 80-100w, you don't want it to overload the psu and take out the rest of the blades).

You could also bring in front of the 'case" the leds if you want to and a reset switch... push buttons are 10-30 cents each, leds are a few cents, ribbon cable is cheap.. it would cost you 10-20$ to make your case.

With 2 sticks of ram and one hdd, each blade would use less than 40w, because the cpu won't be at 100% load all time, but even if you budget 50w for each blade, you can safely power 10 blades from that 600w psu (it's not wise to keep it running at 600w even if rated for so much). That's $15 per blade for the power supply.
With the 53$ 300w power supplies, you'd be getting close to 10$ per blade for the power supply.

I assume that if the power supplies are adjusted to the absolute lowest voltage output possible, and to account for the load, it will be within tolerance of the 19V DC input. If it fries I just send it back! "Oh, it didn't work, I don't know why!..."

Reliability wise how would one of the Digikey adapters? Will it end up being more efficient long term? It says 87% which is fine. Will it last a long time? Because if I run multiple servers off one supply, if it goes out, I have a bunch of pissed off people.

I like your thinking though - I can end up spending about the same amount per server on a larger scale (more on CPU and mobo but less on case and PSU)

[mariushm]

Re: Custom Server Power Distribution Supply

Yeah, the thing is.. that eBay power supply is just a regular switching power supply.

Note that it says "for led strip light" - this refers to those strips of leds that have one current limiting resistor for every 3 leds, or something to that effect. So the strip itself does the current limiting, the strip is just a plain 12v load.

They're using the "led strip light" keywords as marketing, because people are noobs and search for led strip light power supply, they don't search for "industrial ac dc 12v power supply".

It's still a generic Meanwell (or some other chinese brand) 12v power supply, based on old half bridge or some other similar design, with poor power factor correction or poor efficiency.

You also have the idea that since the cpu is passively cooled, you don't need fans. False... the dc-dc converter inside the case and the heatsink on the cpu relies on cool air from outside the case to move through the case and cool itself. If you have a bunch of these in close proximity, there won't be any cool air outside and the systems will overheat. You'll still need some forced cooling to push cold air around those otherwise those cases will just screw with the cooling.

-

The more I think about it, the more I like that Asrock board with 19v DC input.
You could get some thicker aluminum sheets (maybe the size of mATX or ATX boards), drill some holes for some aluminum/steel spacers and screw the mb on that sheet of aluminum. Leave some space in front for 2 x 3.5" hard drives, that you can attach the same way, with some spacers. You made yourself a "blade server".

Now you can make a simple case out of some wood or other material, and simply have some channels on top and bottom spaced evenly. You can now slide the whole aluminum sheet in one of those channels.

At the end of the case, you only have the DC in jack and the network cable, and your blades will be nicely spaced so that you could screw on the end of the "case" a few 120mm fans to blow air through the blades, keeping the cpu heatsink cold and happy.

Here's something similar to what I imagine, only it's made of aluminum or steel and they 3d printed the plastic bits, you can just use some wood and drill holes into wood or aluminum : http://hackaday.com/2013/05/07/3d-pr...unting-system/

One of those 150$ Delta psus is rated for continuous 600w on 24v but it's rated for 1200w for 5s, so it will handle several blades booting up at same time.
It can be adjusted to 21.6v so 90% sure the motherboards will run straight from it.

In front of your case, you can bring a on/off switch for each blade (basically switch in series with the DC in connector). Optionally you could also put a 4-6A fuse in series with each blade (just in case a blade shorts out or dies in some way using more than 4-6 x 20v = 80-100w, you don't want it to overload the psu and take out the rest of the blades).

You could also bring in front of the 'case" the leds if you want to and a reset switch... push buttons are 10-30 cents each, leds are a few cents, ribbon cable is cheap.. it would cost you 10-20$ to make your case.

With 2 sticks of ram and one hdd, each blade would use less than 40w, because the cpu won't be at 100% load all time, but even if you budget 50w for each blade, you can safely power 10 blades from that 600w psu (it's not wise to keep it running at 600w even if rated for so much). That's $15 per blade for the power supply.
With the 53$ 300w power supplies, you'd be getting close to 10$ per blade for the power supply.

[Th3_uN1Qu3]

Re: Custom Server Power Distribution Supply

Stop trying to be cheap. Seriously man...

This.

led power supplies are NOT fixed voltage.
they are fixed current - the voltage will rise and fall as the current use changes.

And this.

I wouldn't let that kind of PSU power any computer equipment - you will be in for a VERY nasty surprise if you attempt to do that.

[stj]

Re: Custom Server Power Distribution Supply

led power supplies are NOT fixed voltage.
they are fixed current - the voltage will rise and fall as the current use changes.

[mariushm]

Re: Custom Server Power Distribution Supply

Stop trying to be cheap. Seriously man...

In the first place, if you don't have those cases already, don't buy those.

The ebay power supply will do what it says but at low efficiency and with shitty power factor correction. Maybe 80% efficiency if you're lucky.

As it's designed for leds, it may not have some protections normal power supplies have. Also, it does NOT have 3 outputs, those terminals are simply tied together, the psu has those terminals simply as a feature, as design.. there is space on the back so they put them there. There's a single 12v output of up to that many amps on it.

Buy a decent ATX power supply that uses dc-dc converters for 5v and 3.3v, such a power supply can deliver all the rated power on 12v.

A $100 Seasonic G750 can do up to 744w on 12v without breaking a sweat.

Even if the servers average at 16w, you can't just multiply. If the servers use classic hard drives, such a hard drive uses up to 2A for a couple of seconds when it starts up.

If you connect several such servers at a single power supply, you have to keep this in mind... if there's a power failure and you connect 10 such servers to your 20A ebay special, you're suddently going to have 4 amps times 10 servers or about 40A pulled from that power supply - it's either going to brown out or die. That's why you have that 5A power supply, even if the "server" averages 16w.

A very simple trick would be to simply use a microcontroller and a few 12v relays to implement a sequential boot for those servers. microcontroller starts, then every 5s or so it triggers a relay which connects a server to the power supply. This way each separate hdd has time to booth up. Problem solved.

Relays are cheap, less than $1 if you buy in quantity: http://www.digikey.com/product-detai...1012-ND/280369

Still, you're going to lose energy in the power supply in the server case also.

If you're really smart you could go with something like this:

$59 : ASRock AM1H-ITX AM1 HDMI SATA 6Gb/s USB 3.0 DC-In/ATX Power Input Mini ITX AMD Motherboard

http://www.newegg.com/Product/Produc...-491-_-Product

AM1 socket Mb, 19v +/- 10% DC in OR regular atx, you can power the hdd directly from motherboard. You won't have a DC-DC converter in the small case (as the Sentey does, and see reviews to read how well that works) to create 5v and 3.3v and waste power on that and lose watts due to efficiency, those are built into the motherboard already

DRAM HDD Estimated Adapter Power
1 1 41W
1 2 56W
2 2 60W

Standard DDR3 memory, up to 16 gb, video in cpu, gigabit lan, generally better features than intel boards.

$50 : http://www.newegg.com/Product/Produc...82E16819113365

AMD Athlon 5150 Kabini 1.6GHz Socket AM1 25W Desktop Processor AMD Radeon HD 8400 AD5150JAHMBOX

Same processing power as your Intel, maybe a percent or two faster, definitely faster if you pair it with 1600 Mhz memory instead of the 1333 Mhz or 1066 Mhz you're limited to with that so-dimm on Intel.
These Kabini are 25w rated, in reality they're going to use about 20w or less, so the whole system is going to use 30-40w instead of your 16-20w.

You can use directly 19v laptop adapters for each one, or you could buy a 18-20v power supply with lots of amps and power the systems from that single psu, without having to buy cases and so on...

Later edit: Considering it's 19v +/- 10%, that means the board should accept even 21v. It wouldn't surprise me if the board would actually run just fine off 24v, which is a standard voltage for power supplies, so you could find 24v 600w power supplies (or something like that at atx power supply prices). And even if you don't, you could also put 2 or 3 beefy (high current) in series before the dc in connector, to drop about 0.8-1v on each diode, so that the board would see 19-21v.

For example,

150$ for 600w (if you buy 10, ~ 165 for one): http://www.digikey.com/product-detai...068-ND/4386539
53$ for 300w (better value, again if you get 10.. works out at ) : http://www.digikey.com/product-detai...077-ND/4386548

Most of these 24v power supplies can even be adjusted to output between 22-24v+ (The 600w delta above at 150w can be adjusted down to 21.6v) so if you adjust it down to around 22v or less you may even be able to skip those diodes.

The jack + cable is cheap, under 3$ : http://www.digikey.com/product-detai...2186-ND/568577 ... the jack alone is under 50 cents , but then you'd have to buy cable and solder it.

[shovenose]

So, let's say I have a lot of little computer/servers in these cases:
http://www.newegg.com/Product/Produc...82E16811321014
By default they include some generic 12V 5A brick. They have internal power boards too that take that from 12V and turn it into all the other voltages the computer needs.

Specs are going to be as follows:
-Intel J1900 Quad Core 2GHz 10W CPU
-2x4GB DDR3 SO-DIMM
-500GB or 1TB 2.5" HDD, or a 2.5" SSD

So very modest power requirements. They are fanless too which is great.
Now let's assume each server consumes on average 1.5A - that's 16W. The probably inefficient, likely low quality 12V 5A brick is pointless then.

I found this product, my only concern is, do we trust it?
http://www.ebay.com/itm/12V-20A-240W...item3cd0b1f19a

But that's 20A. I could power 13.333 servers if I assume they take 1.5A. Let's just do 12 because it's an easy number. The power supply in that link has three outputs each, meaning each V+ and V- would go to four servers. Does that make sense and would that work?

Would it be more or less efficient just to use the included power bricks or this 20A power supply? Is there any fundamental problem with my thought? Is there a cheaper more efficient design I could use?

Thanks!