PSU, 30 hard drives - single vs multi-rail?

thepregnantgod · Feb 5, 2016

I am trying to put 30 hard drives in my home server. I'm using this PSU (Kingwin Mach 1 1000 Watts) but am experiencing some of the drives dropping or not spinning up. I put the drive in my main rig and all is well.

So I suspect a PSU problem. Some of my research says the above PSU is a multi-rail PSU. Does that impact how I daisy chain my drives? I'm using 4xSATA splitters (usually 2 of those) to each of the SATA/Molex cords into the PSU.

The drives are all green 5400rpm drives.

Also, regarding spinup - I can stagger the spinup, but would prefer not to. And that's not the issue either because I boot the system with 20 drives fine - then while in Windows connect power to the remaining drives (thus a stagger so to speak) and they won't read.

Math Geek · Feb 5, 2016

the multi rail refers to the 12v rail which the hdd's don't use. it's possible you are overloading the rail they are on but i'd have to verify the power draw. you can search the specs for the drives and see what power they draw and do some quick math to ensure they are not overdrawing the power supply.

it is unlikely but a possibility with so many drives.

USAFRet · Feb 5, 2016

30 drives?

1. Why?
2. What data ports are you plugging these into?
3. How large are these, and 3.5" or 2.5" or SSD?
4. You need a better PSU

thepregnantgod · Feb 5, 2016

USAFRet:
1. Because I can? Because 100TB is not enough storage? And because I have a redundant media server.
2. I'm plugging these into 10 SATA ports on my mobo, 16 ports on a LSI SAS card, and 8 ports on a Supermicro SAS card
3. 3.5" green drives (from 3TB up to 8TB)
4. 1000 Watts easily covers the drives - I have no video card attached (it's headless) and the CPU is not overclocked. Even at boot - my UPS which shows wattage it's pulling maxes out at 289watts.

USAFRet · Feb 5, 2016

"Better PSU" does not mean more watts.
It means better quality.

thepregnantgod · Feb 5, 2016

USAFRet, I know Kingwin is not top of the line. That's why it isn't in my main rig - where I use a Corsair 1200AX Professional Gold.

But it was SLI certified, 80plus Bronze, and it's only powering green drives. I thought it would be sufficient.

ko888 · Feb 5, 2016

For the Kingwin Mach 1 1000W PSU all eight 4-pin Molex peripheral and all eight SATA power connectors are on the 12V6 rail which is limited to 20 Amps.

SATA power splitters just make the overload situation worse.

What you need to worry about is the startup current of the HDDs. The startup current of the HDD is much higher than the steady state operating current once the HDD is up and running. If all 30 HDDs powered up at the same time they would definitely overload the 12V6 rail.

What's the specific brand and model number of the green 5400rpm HDDs?

A single WD Caviar Green has a startup current of 1.75 Amps for the 2TB model and 1.78 Amps for the 2.5TB and 3TB models. Thirty of those drives all starting up at the same time would be well beyond what the Kingwin Mach 1 1000W PSU's 12V6 rail can supply. Once all 30 HDDs have started up though the current draw should be 0.5 Amps or less per HDD and that would be within the Kingwin Mach 1 1000W PSU's 12V6 rail capacity.

thepregnantgod · Feb 5, 2016

Okay, since experts are actually answering - how many drives (via splitters) can I put on a single rail coming out of the PSU box? I'm going to switch my Corsair 1200AX gold (which should be overkill) to the media server. But I know I still can't hook up all 30 drives on a single rail. So how many would be reasonable? I'm thinking in groups of 4 since those are the splitters I have.

USAFRet · Feb 5, 2016

Split those drives into 2 different PC's.

thepregnantgod · Feb 5, 2016

USAFRet, I tried that for a while but that didn't really work. I would have to keep both machines on 24/7 if I wanted them to be a media server/file server. Even if I had one machine with primary files and use the other machine as a backup that would still require me to put RAID cards, etc. in the main rig and once I mess with it and take it down then I lose sync between the two systems.

It's just easier to have all the drives in one box.

ko888 · Feb 5, 2016

The Corsair AX1200 has a single +12V rail that is rated for 100 Amps. No problem there in handling all 30 HDDs.

thepregnantgod · Feb 5, 2016

I'm trying to learn this...

So the specs for the Kingwin 1000 are here: http://www.rmac.kingwin.com/products/cate/power_supplies/abt_1000MA1S.asp

It says max output is 81 amps. If every drive pulls 1.78 x 30 shouldn't I still be within limits?

But, it has 2 rails with Molex and 2 rails with SATA. Is this how you're getting 20amps / rail? If that is how it works it allows me to plan a bit better for my wiring.

ko888 :

ko888 · Feb 5, 2016

thepregnantgod :

Look at the bottom of this page in the review for that PSU:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=155

All of those 5-pin modular connectors on the modular panel of the PSU are wired to the 12V6 rail. That is a physical limitation you can't change.

thepregnantgod · Feb 5, 2016

ko888, you truly are a Grandmaster. I'm learning. So, I'm going to search for the same info on my Corsair AX1200 Gold to see if that will solve the problem.

ko888 · Feb 5, 2016

thepregnantgod :

As I've said, above, you won't have that problem with the Corsair AX1200.

thepregnantgod · Feb 5, 2016

Thanks. I just purchased the EVA Supernova 1600 T2 so I can swap the Corsair 1200 over to my server but I think the EVA Supernova might be overkill for my system. I really only have 2 GTX Titan X connected to an overclocked 5930K and 4 SSDs/M.2 -

ko888 · Feb 5, 2016

thepregnantgod :

System Power Supply Requirements for two GeForce GTX TITAN X graphics cards in 2-way SLI mode
• NVIDIA specifies a minimum of a 850 Watt or greater system power supply. (Minimum system power requirement based on a PC configured with an Intel Core i7 3.2GHz 130 Watt TDP processor.)
• the system power supply must also have a maximum combined +12 Volt continuous current rating of 60 Amps or greater
• the system power supply should also have at least two 75-Watt 6-pin and two 150-Watt 8-pin PCI Express supplementary power connectors.

Someone Somewhere · Feb 5, 2016

Note that the entire point of having multiple rails is to make sure the current through any one wire/connector can't be too much. If you try to run all your drives from SATA ports, while you won't have issues with the overcurrent protection kicking in, you may still see serious voltage drop and get very warm wires.

You really need a proper server-grade disk bay, which has all the cabling going straight to SATA ports. In a desktop PSU, it's all GPUs and CPUs and everything else is an afterthought.

jimmysmitty · Feb 8, 2016

Someone Somewhere :

I agree. Problem is I don't know of any 30 bay server racks. Most I know of are 2U or 3U. Most 2Us can support 12 3.5' HDDs and a 3U would only add another 6 3.5" HDDs to that mix for 18 total. But they are designed better as they have a backplane connected to the system that helps handle the power.

thepregnantgod · Feb 8, 2016

I have a 16 (4x4) Server rack - Norco I believe - but the drives got too hot (even the green ones). So I built a custom open air rack for all 30 drives with 8 140mm fans cooling them. Now, all 30 drives run at an avg of 34 degrees Celsius under load. In the rack they'd get up to 55 degrees.

Cokie69 · May 1, 2016

Hi guys, I'm following this thread with a lot of interest because I'm also building a hard disk enclosure for x14 SATA disks of different sizes. I have to admit though, I'm quite lost with some of your replies as I am not familiar at all with the calculations of watts and amps nor the concept of rails, etc.

Since I have a pretty tight budget I am not looking at top of the range PSUs like the ones you mention but to a simple, cheaper (yet not cheapest!) PSU that "can do the job".

As per ko888 answer re:startup current, am I right to assume the the most important parameter I should be looking at is the PSU max amperage load in order to know whether it'll be able to power up all my disks? Assuming say x14 3Tb green disks with an average of 1.78A per disk -which, on power up I read that can drain as much as 3A per disk- so that'require a PSU supporting at least 42A (14x3A), yes? And as per watts, is it correct to assume the general rule of thumb for about ~25 watts per 7200 rpm drive?, if so, 14HD x 25W would yield a mere 350W requirement, hence a small PSU.

In all, and taking into account amperage loads of at least 40A on power up, where I am now (in Europe), these are the PSUs I can easily get in the 'corner shop' at a decent price... which one do you think would fit the bill?

(35€) TACENS RADIX ECO III 650W http://www.tacens.es/power-supplies/power-supplies/radix-eco-iii-650/
(45€) MARS GAMING MP700 700W http://www.marsgaming.eu/en/products/mp700.html
(60€) BE QUIET L8 500W http://www.bequiet.com/en/powersupply/389
(63€) TACENS RADIX VII AG 700W http://www.tacens.es/power-supplies/power-supplies/radix-vi-ag/
(65€) FSP HYPER 600W http://www2.fsplifestyle.com/home/product.php?rKey=P161000095

Needless to say I will be using splitters to connect all the 14 drives, of course!... would that make a lot of difference on the power requirements (watts/amps) ??

Thanks a lot for your input and please, note I'm a newbie in all this!

thepregnantgod · May 1, 2016

Are your drives Green or regular? That determines the amount of draw. Additionally, are you running them all off the motherboard or a RAID expansion card? If the latter, you might need to set them to stagger spinup (one powers up, then another, etc.). It's a little slower but prevents them from drawing too much power at boot and either crashing, messing up a drive, or corrupting data. I've had all of those experiences before - and nothing is more frustrating when you have them in a RAID and one drive goes bad - even RAID 5 because rebuilding 50TB with green drives takes forever!

Cokie69 · May 1, 2016

... most of them are green (at least 10 out of 14), and no, I'm running them as JBOD on plain eSATA 5x1 port multipliers.

turkey3_scratch · May 1, 2016

The thing is, I don't see how rail distribution would be causing an issue because OCP physically shuts down the power supply. If his PSU is not shutting down, then OCP is not being triggered.

Let's not forget that hard drives use 5V also.

Someone Somewhere · May 2, 2016

turkey3_scratch :

Undervoltage would be my guess.

PSU, 30 hard drives - single vs multi-rail?

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