Power supply for Dell workstation

[newpain01]

Hi everyone!

I am new here, joined a while back to learn more about TrueNas and so far I'm enjoying the forum!

I found a few great threads about power supplies here on the forum and while I learned a lot, I still have some questions more specific to my setup.

My server is a Dell Precision T3610 workstation with an Intel Xeon E5-2650L v2 (TDP 70W) and 96GB ECC RAM. The GPU is a Nvidia Quadro K600 (Max Power Consumption 41W). The machine has a stock DELL 685W power supply that is 80 Plus Gold, plug and play, similar to a rack server PSU. The output is 18 Amps on 12V and 4 Amps on 5V. Some photos from the PSU here.


The PSU only has 3 SATA power connectors (2 on one cable, 1 on the other). Both cables are split from the white 24 pin connector, picture below.


I am running Proxmox with 4 SSDs in ZFS RAID 1 (2 are for Proxmox and 2 are for the Virtual machines). They are powered from 18 gauge Y SATA splitters, like these.

I have TrueNAS Core installed as a virtual machine and I am getting 5 x 14TB hard drives to use as storage for the NAS in RAIDz2. I will be adding one more 4-6TB hard drive to use for surveillance footage, so total should be 6 HDDs + 4 SSDs.

Now, I don't feel comfortable daisy chaining these power connectors as I read they can cause an issue. I believe the PSU can handle the load, though.

What are my options here? Is there any way to re-wire this properly (I am comfortable with electronics, soldering, wiring and so on) or do I have to replace this PSU?

If I have to get a new PSU, what would be the best option considering my use case? And what form factor can fit here, considering this is not a standard ATX power supply?

Appreciate any advice!

 

[rvassar]

The problem here is the ATX PSU's multi-voltage output is somewhat an anachronism. Most server form factor PSU's produce the bulk of their output on the +12v rail and let the motherboard & various daughter cards figure out how to convert to +5/+3.3/+1.5v , etc... You did post one possible solution in one of your pictures. The "4044" pic shows an 8-pin GPU accessory power plug. But I believe it only provides +12v, leaving you no +5v, which your drives will need.

As for replacing the PSU, that becomes problematic for the same reasons I just mentioned. The system is engineered with the PSU duty split between the actual PSU, and the local voltage converters near the point of use on the planar. Trying to drop a standard ATX PSU in would be more effort than just moving the 5 x 14Tb drives to an external SAS JBOD.

 

[newpain01]

Thank you for the reply!
You are right, the 8-pin GPU plug only provides 12V, the cable is yellow/black - I unplugged it. I can splice in a voltage convertor to convert down to 5V, do you think that will work? It's so hacky, I was hoping for a cleaner solution.

Regarding the external SAS JBOD enclosures, how are they powered? Do they have their own power supply? In that case, how are the drives powered down when idle? Also, my hard drives are SATA, not SAS.
I have an enclosure from an old HP StorageWorks server that can fir 14 HDDs and I can use that with a dedicated power supply, but my concern is powering down the HDDs when they are idle, I don't want them spinning 24/7.

 

[rvassar]

Thank you for the reply!
You are right, the 8-pin GPU plug only provides 12V, the cable is yellow/black - I unplugged it. I can splice in a voltage convertor to convert down to 5V, do you think that will work? It's so hacky, I was hoping for a cleaner solution.

I would not recommend that solution at all.

Regarding the external SAS JBOD enclosures, how are they powered? Do they have their own power supply? In that case, how are the drives powered down when idle? Also, my hard drives are SATA, not SAS.
I have an enclosure from an old HP StorageWorks server that can fir 14 HDDs and I can use that with a dedicated power supply, but my concern is powering down the HDDs when they are idle, I don't want them spinning 24/7.

A proper SAS JBOD shelf will have it's own PSU. The power save mode for the drives is a function of the drive itself. If you configure them to spin down when idle, they'll do so in a JBOD enclosure as well.

You can actually build one yourself from backplanes and various PC cases and bits if you'd like a DIY project. The bit you're missing about SAS & SATA... All SAS controllers will speak to a SATA drive. SATA controllers only speak to SATA drives. They are electrically compatible (nearly identical!), the plugs and pinouts are the same on the drives. The SAS drive have a plastic bridge between the data plug and the power plug to act as a lockout key, preventing them from being plugged in to a SATA cable. The only other caveat is SAS runs the voltage a bit higher so it can have cable runs longer than 1m. If you use SATA drives in an external enclosure, you'll want to keep the cables short.

 

[newpain01]

Got it.
One thing I forgot to mention is that I already have an LSI SAS HBA 9211-8i IT Mode card in this server. It has 2 SAS ports and 2x 1m cables that split into 4 SATA cables, so I can connect up to 8HDDs on that.

So, basically I can install the HDDs in the HP StorageWorks case, put a dedicated ATX power supply for them and connect them with the cables directly to the LSI card, is that a good solution in this case?
The only issue I see here is the second PSU has to be switched on and off manually and will not be controlled by the motherboard.

 

[newpain01]

This is how that enclosure looks like:

 

[rvassar]

Got it.
One thing I forgot to mention is that I already have an LSI SAS HBA 9211-8i IT Mode card in this server. It has 2 SAS ports and 2x 1m cables that split into 4 SATA cables, so I can connect up to 8HDDs on that.

So, basically I can install the HDDs in the HP StorageWorks case, put a dedicated ATX power supply for them and connect them with the cables directly to the LSI card, is that a good solution in this case?

That sounds like a good solution to investiagte. Poke holes at it, get a solution you can work with... Don't settle.

The only issue I see here is the second PSU has to be switched on and off manually and will not be controlled by the motherboard.

There's probably a way to solve this. Maybe an IP wall socket switch, or network addressable power strip. Might be tricky getting TrueNAS to bring it up before it tries to import the pool, but worth a look.

 

[newpain01]

That sounds like a good solution to investiagte. Poke holes at it, get a solution you can work with... Don't settle.



There's probably a way to solve this. Maybe an IP wall socket switch, or network addressable power strip. Might be tricky getting TrueNAS to bring it up before it tries to import the pool, but worth a look.

Oh, I'm the kind of person that never settles, always tinkering with something. I'll figure this out.

Using a smart socket switch sounds like a great idea. I don't need TrueNAS to bring it up. This server is running Proxmox with a bunch of virtual machines and containers, one of which is Home Assistant. I can figure out how to turn on a smart socket when the Home Assistant VM boots up and make it boot before the TrueNAS VM, that way the HDD array will be ready when TrueNAS boots up.