Staggered HDD Start

[Computerz]

Hi,

I plan on having 24 drives in my server. Going with 12 for now, but I want to be ready to add an additional 12 at any time.

The HDDs in question are the Seagate 7E10 8TB ST8000NM017B. Here are the specs for their spin up power draw:

Here is the current profile (which looks to be cut off prematurely. You can see the current profile for the X20 drives in the image below the 7E10 profie and I’m guessing the 7E10 profile is similar to the X20).

So by my calculations:

5V rail consumes 4.4W per drive. For 12 drives that’s 52.8W. For 24 drives that’s a whopping 105W. More than what 750W PSU I’m looking at can deliver on the 5V rail.

12V rail consumes 26.58W per drive. For 12 drives that’s 318.96W. For 24 drives, that’s 637.92W. Again, getting close to the limit of a 750W of the PSU just in drives – probably exceeding the 744W rating of the same 750W PSU when factoring in all the other stuff I want to put in the server.

So basically, it seems like when you go higher drive counts, you have no choice but to go into the staggered start territory. The internet unfortunately doesn’t have much info on this. And some of it is conflicting. I only really found two imperfect, good sources:

Staggered Spinup and Its Effect on Power Draw - 45Drives Blog

What's the deal with staggered spin up?

So I’m kind of working off fumes on how staggered starts can happen. From what I’m reading there are 3 options.

1.) If you’re running SATA drives, then PUIS is an option. However the Seagate 7E10 8TB ST8000NM017B (Product Manual) don’t appear to support PUIS. I have looked at other drives from Seagate and it’s quite bizarre, but even the lowly Barracudas support PUIS, but these 7E10s don’t appear to. The Exos X20 (Product Manual) however, appear to. So it seems this option is out for me. Which leads me to the second two options:

Pin 11. Apparently you can implement staggered start using Pin 11 from two places, the HBA or the backplane.

2a.) Backplane controlled pin 11 logic. I’m not sure whether backplanes can do this or not, but the manufacturer of the backplane that I’m interested in said the backplane is dumb and only passes through stuff and doesn’t offer any staggered start capability. They said that it’s a HBA thing.

2b.) So on to the HBA option. But I was wondering: I read that to first enable staggered start, you need to first ?boot into? the HBA software/BIOS thing and enable the staggered start. For this you would basically require starting all the drives for the first time without using staggered start. The obvious work around to this would be to boot with 1 drive attached, turn it on, then plug in all the remaining drives. I’m just theorising at this point.

Anyway, looking for someone to explain this whole thing to me. I’m pretty lost to be honest. At least on page 31 of the Seagate 7E10 Product Manual it states there is a pin 11 implemented. So it seems, at the very least I’ll be able to use HBAs for staggered start if PUIS isn’t available.

[EniGmA1987]

@Computerz

5V rail consumes 4.4W per drive. For 12 drives that’s 52.8W. For 24 drives that’s a whopping 105W. More than what 750W PSU I’m looking at can deliver on the 5V rail.

12V rail consumes 26.58W per drive. For 12 drives that’s 318.96W. For 24 drives, that’s 637.92W. Again, getting close to the limit of a 750W of the PSU just in drives – probably exceeding the 744W rating of the same 750W PSU when factoring in all the other stuff I want to put in the server.

Or, look at buying a 1200-1500w power supply that can provide the proper amperage for a large number of drives. Something like the Corsair HX1200 that provides a nice 30A on the 5v rail.

[H-i-v-e]

I have an 16 port SAS/SATA HBA in my computer with an 750W power supply and 18 drives. It works fine, the HBA (in IT mode) does a staggered spin up when you turn the computer on without me needed to do anything. I bought it pre-flashed, put it in, and it seems to have been the default behavior. Form that experience I would derive that most HBA should be either do it by default or have an option to configure this. I meant enterprise servers face this issue all the time.

[Exard3k]

@H-i-v-e

Form that experience I would derive that most HBA should be either do it by default or have an option to configure this.

I had some drives connected via on-board SATA controller and they start staggered as well. So I assume it’s more a feature of the backplane than a feature of the controller. I have a simple non-active backplane.

[Computerz]

@H-i-v-e

I bought it pre-flashed, put it in, and it seems to have been the default behavior. Form that experience I would derive that most HBA should be either do it by default or have an option to configure this. I meant enterprise servers face this issue all the time.

Yer, I’m learning in that direction. Even for the first 12 drives, the drives I’m planning on using are already pretty power hungry.

@Exard3k

I had some drives connected via on-board SATA controller and they start staggered as well. So I assume it’s more a feature of the backplane than a feature of the controller. I have a simple non-active backplane.

I had a read of the manual for the motherboard, it doesn’t appear to have staggered start. I couldn’t find any features/options/info on this in the manual so I’m assuming it’s not available.