PSU for 28 - 32 Harddrives

ATWindsor · Post by **ATWindsor** » Wed Jun 27, 2007 10:22 pm

I'm getting a PSU to drive 28-32 HDs, as a rule of thumb i have assumed 1 A at 5V and 2A et 12V during spin-up, and i have run into a unexpected potential problem, the 5V-line. Seaonic and PCP&C both operate with a 5V at 30A even in their most powerful PSUs, is this enough during the spin-up-fase? (remeber i have the rest of the computer to power also).

Furthermore I have seen a couple of disturbing tests where the seasonic 5V has dropped voltage with more than 5% when closing up to full load. Any input on this?

Suggestions for other high-quality PSUs are also wecome (it's nice if it doesn't sound like a jet, but lets face it, 30 HDs will make a lot of noise, so it not needed to be extremly quiet)

AtW

daamain · Post by **daamain** » Thu Jun 28, 2007 12:59 am

You can try Cooltek CT500, I believe it has 45A on 5V line. Altough I think 30A is enough for your HDs.

Trekmeister · Post by **Trekmeister** » Thu Jun 28, 2007 3:14 am

Are they SCSI or IDE drives? I know that at least SCSI drives/controllers supports so called staggered spin up, meaning not all drives start at the very same time in order to reduce peak startup current draw.

ATWindsor · Post by **ATWindsor** » Thu Jun 28, 2007 3:32 am

daamain wrote:You can try Cooltek CT500, I believe it has 45A on 5V line. Altough I think 30A is enough for your HDs.

Do you know how many amps it has on 12V? I have difficulity fonding info about it that is not german. I was thinking something in the line of 60A was nescessary, but thts probably a bit of overkill. (seeing as HDs are rated at 2A on the 12V-line only on spin-up).

AtW

ATWindsor · Post by **ATWindsor** » Thu Jun 28, 2007 3:35 am

Trekmeister wrote:Are they SCSI or IDE drives? I know that at least SCSI drives/controllers supports so called staggered spin up, meaning not all drives start at the very same time in order to reduce peak startup current draw.

Its Sata, my controller supports staggerd spin-up, but I think the drives have to as well. I have also heard rumours that most sata-cables are terminated in a way that renders the wire for staggered spin-up unsuable, and thus not working. But I have no idea if this is the case.

Based on experience, it seems just having a lot of drives, connect to a diffrent places (controller/mobo) seems to cause the drives not to start at exactly the same time.

AtW

continuum · Post by **continuum** » Thu Jun 28, 2007 4:03 pm

Staggered spin-up requires backplane support as well, if memory serves.

However so long as your controllers are delayed in start, that generally works.

http://www.storagereview.com/HD501LJ.sr?page=0%2C5

Shows a bit less than +1A on +5v at startup.

32 drives is quite a lot, although you should be ok on start-up with just +30A on the +5v. If your goal is a true enterprise-grade box I would be looking at units from Delta, Zippy/Emacs, Etasis, and NMB. We build 5U 25-drive systems here on a regular basis with 950W 2+1 Zippy PSUs that should easily handle 32 drives...

murtoz · Post by **murtoz** » Thu Jun 28, 2007 4:17 pm

ATWindsor wrote:
daamain wrote:You can try Cooltek CT500, I believe it has 45A on 5V line. Altough I think 30A is enough for your HDs.
Do you know how many amps it has on 12V? I have difficulity fonding info about it that is not german. I was thinking something in the line of 60A was nescessary, but thts probably a bit of overkill. (seeing as HDs are rated at 2A on the 12V-line only on spin-up).

AtW

Here's the specs from one of those german reviews:
+3,3V: 30A
+5V: 45A
+12V1: 20A
+12V2: 20A
-12V: 1A
+5V SB: 3A

So should be a total of 40A on +12V.

Just out of curiosity, is this SCSI/SATA/SAS, and which controllers are you using? SATA controllers can support staggered spinup, but it is not a requirement so check the specs. Same for the disks. I don't think the backplane needs to support this though.

ATWindsor · Post by **ATWindsor** » Thu Jun 28, 2007 9:29 pm

continuum wrote:Staggered spin-up requires backplane support as well, if memory serves.

However so long as your controllers are delayed in start, that generally works.

http://www.storagereview.com/HD501LJ.sr?page=0%2C5

Shows a bit less than +1A on +5v at startup.

32 drives is quite a lot, although you should be ok on start-up with just +30A on the +5v. If your goal is a true enterprise-grade box I would be looking at units from Delta, Zippy/Emacs, Etasis, and NMB. We build 5U 25-drive systems here on a regular basis with 950W 2+1 Zippy PSUs that should easily handle 32 drives...

Thanks for the link. I'm not sure if my goal is a "true enterprise-grade box". I just wants something that works well. It will not be rack-mounted. So what do you think there is to gain on getting one of the PSUs you mentioned, compared to a "normal" cpu? (besides i suspect, a lot of additional noise

)

AtW

ATWindsor · Post by **ATWindsor** » Thu Jun 28, 2007 9:30 pm

murtoz wrote:
ATWindsor wrote:
daamain wrote:You can try Cooltek CT500, I believe it has 45A on 5V line. Altough I think 30A is enough for your HDs.
Do you know how many amps it has on 12V? I have difficulity fonding info about it that is not german. I was thinking something in the line of 60A was nescessary, but thts probably a bit of overkill. (seeing as HDs are rated at 2A on the 12V-line only on spin-up).

AtW
Here's the specs from one of those german reviews:
+3,3V: 30A
+5V: 45A
+12V1: 20A
+12V2: 20A
-12V: 1A
+5V SB: 3A

So should be a total of 40A on +12V.

Just out of curiosity, is this SCSI/SATA/SAS, and which controllers are you using? SATA controllers can support staggered spinup, but it is not a requirement so check the specs. Same for the disks. I don't think the backplane needs to support this though.

Tahnks for the data. It's sata-drives, in addition to the mobo, I am using an areca 16-port controller (arc-1260).

AtW

daamain · Post by **daamain** » Fri Jun 29, 2007 12:26 am

Unfortunately you can't totalize 12v lines. Cooltek CT 500 has 33A on the 12v. Should be enough.

ATWindsor · Post by **ATWindsor** » Fri Jun 29, 2007 4:43 am

daamain wrote:Unfortunately you can't totalize 12v lines. Cooltek CT 500 has 33A on the 12v. Should be enough.

You think so? Many Hs draws around 2A from 12V during startup, and more than 1A during use. To be honest I am worried about the headroom with only 33A

AtW

daamain · Post by **daamain** » Fri Jun 29, 2007 5:31 am

I checked again and it may be not enough... But you would need a PSU with over 60A on 12v to power all the drives during startup. You can either:
a) Get such a PSU
b)

Are they SCSI or IDE drives? I know that at least SCSI drives/controllers supports so called staggered spin up, meaning not all drives start at the very same time in order to reduce peak startup current draw.

But with those I can't help you, however it seems to be a better idea than a 800-900W PSU

ATWindsor · Post by **ATWindsor** » Fri Jun 29, 2007 6:08 am

daamain wrote:I checked again and it may be not enough... But you would need a PSU with over 60A on 12v to power all the drives during startup. You can either:
a) Get such a PSU
b)
Are they SCSI or IDE drives? I know that at least SCSI drives/controllers supports so called staggered spin up, meaning not all drives start at the very same time in order to reduce peak startup current draw.
But with those I can't help you, however it seems to be a better idea than a 800-900W PSU

Well, as mentioned, my controller du support staggered spin-up. However I am not sure if it is normal for sata-drives to do so, or if the cable-termination problem i mentioned i a real issue or not.

I was thinking about the seasonic m700, or x900, wich are not that expensive. However the reviews wich showed bad 5V-performane are a bit disturbing.

AtW

ATWindsor · Post by **ATWindsor** » Fri Jun 29, 2007 6:32 am

Here are som potenially useful details about the cable-problem:

"Basically, it is controller default supports, no additional setup needed, but you will need to check your system hardware. First, you need to check the drive specification to make sure this drive supports Stagger Power On feature. Second, you need to check the drive back-plane connector. ( 7-pin SATA signal + 15-pin power )

Check the Pin 11( the 11's pin of 15 pin power connector ) is pull-low, floating or pull-high ? According to specification, the P11 must be floating or pull-high to support Stagger Power On feature. If you don't use back-plane, just use a 4-pin to 15-pin translation power cable. This kind of cable normally pull-low P11 pin, you will not able to use Stagger Power On feature."

http://faq.areca.com.tw/modules/smartfa ... p?faqid=94

I'm not sure what the practical implications of this is in a "normal" system (I have no backplane), so if anyone could shed any light on this it would be nice.

AtW

continuum · Post by **continuum** » Fri Jun 29, 2007 10:44 am

Practical implementation is that the drives will always be powered-on, without a backplane and a direct connection to the PSU instead, the drives will NOT support staggered spin-up.

You're talking about +65A @ +12v on startup and +35A or so on the +5v line, which is pretty large for a consumer-grade PSU. I don't have any experience building systems with consumer-grade PSUs that large, even though a very, very good consumer-grade PSU should be able to do this. I would look at PC Power and Cooling and see if they can do anything for you; if not I'd look at either rigging dual power supplies to ensure you can get enough +5v current (not exactly professional, but since this isn't an enterprise-grade box you're don't care?) or looking at a real enterprise-grade PSU.

ATWindsor · Post by **ATWindsor** » Fri Jun 29, 2007 1:00 pm

continuum wrote:Practical implementation is that the drives will always be powered-on, without a backplane and a direct connection to the PSU instead, the drives will NOT support staggered spin-up.

You're talking about +65A @ +12v on startup and +35A or so on the +5v line, which is pretty large for a consumer-grade PSU. I don't have any experience building systems with consumer-grade PSUs that large, even though a very, very good consumer-grade PSU should be able to do this. I would look at PC Power and Cooling and see if they can do anything for you; if not I'd look at either rigging dual power supplies to ensure you can get enough +5v current (not exactly professional, but since this isn't an enterprise-grade box you're don't care?) or looking at a real enterprise-grade PSU.

Thats was what I was afraid of. However I hope tha fact that the drives on the controller seem to spin up later than the ones on the mobo will save som power. As I said in the first post i have considered PCP&C, but they also have only 30A on 5V. Do you think they would be a better choiche than seasonic? And I have heard rumors that the PCP&C-PSUs are pretty noisy?

AtW

continuum · Post by **continuum** » Fri Jun 29, 2007 2:10 pm

However I hope tha fact that the drives on the controller seem to spin up later than the ones on the mobo will save som power.

Yeah, that's what I've personally observed as well... however, as the systems I build generally all have backplanes, I'm not quite sure either.

PCP&C's are going to be more noisy, but you're talking 32 HDDs anyway, you're going to get a fair amount of noise.

You may want to contact their sales department directly and see what they can do for you aside from just the stock products on their website.

ATWindsor · Post by **ATWindsor** » Mon Jul 02, 2007 9:49 pm

Not to beat a dead horse here. But I would like to repeat one of my questions. Giving that they are rated for the same current, is there a reason to assume that PCP&C is a better choiche than a seasonic? PCP&C unfortantly are a bit harder to ge by here.

AtW

continuum · Post by **continuum** » Tue Jul 03, 2007 12:06 pm

Not really. Traditionally server-grade PSUs are far more overbuilt than their consumer counterparts, and hence can handle higher peak loads... but the Seasonic stuff is already pretty nice, and PCP&C's consumer-marketed stuff isn't exactly server-grade like what I'm used to either...