Maybe I will look for a PSU with 20 sata and double 3/4 of the connectors.
https://pangoly.com/en/product/lc-power-lc1200p-v3-0 not sure how good this lc power is
Hah but with that cost I could probably just buy the same psu again
Could go a little bit more in depth with the 1,5A limit on the pins and voltage drop etc?
Sata Power pins are different than the crimp pins you use for 24/pcie/eps - they don’t slot in, they just kinda sandwich ontop of each other:
If you look at the pin-out, you’ll see that 3.3v, 5v, & 12v each get 3 pins. Each pin is rated for ~1.5amps if I remember correctly. So 54watts max of 12v, 22w of 5v, ~15w of 3.3v
But if one of those pins isn’t making proper contact, you just lost 30% of your output on that rail.
Edit: again I only answer one of your two questions…
Voltage drop; basically the more load there is on a voltage rail (depending on quality of the PSU), the higher the chance that voltage will drop; ie 5v turns into less than 5v. Hardware generally has some tolerance to voltage fluctuations, but only to a certain point - issues causes by unstable voltage are sometimes much less obvious than ‘computer turns off’.
Corsair RM1200x Shift can power 20 sata drives, and is much easier to work with than a standard ATX power supply. I can vouch that it’s a viable option if one has a wide enough case.
It’s not designed for running 40 HDD though.
mmh yeah this had been my original plan. Replace both my PSUs with ones that support around ~20 drives natively. Preferably with ones under 1000W.
And just sell or reuse the current ones…
buying 20 stata splitters seems ridiculous in hindsight.
That seems indeed to be the best, safe and cheapest option.
I know that the 850x has the same 5V rail capacity as the 1200x, and the same number of SATA connectors (the biggest difference is the 12V rail, if not running a big GPU for AI it should be fine).
No comment on anything else, I’m not knowledgeable enough for my opinion to be taken seriously.
And huge thanks @Fleshmauler you increased my knowledge about this a lot!
Look here:
I’d be looking into a large HD case from Supermicro… or second hand.
24, 45, 60 or 90 bay etc
Yep. This is a solved problem, and suitable hardware is readily available. It isn’t super-cheap, but reasonable if bought used.
Well, if a new case is on the table, a H45 could alos be a nice option.
That one has PCB backpanels, so the sATA power cable issues would also be solved.
Their backplanes are dodgy IMO; Supermicro seem to have much better thought-out kit. But that’s another option.
Are there any particular worthwhile models?
I only read somewhere that shopping for sas1 models and replacing the backplane can get you some godd deals. I don’t want a backplane with a sas chip anyway
A Backpanel is usually a passive component. The connector can be sATA or SAS.
And, as I know, you can use sATA drtives plugged into a SAS Connector, but not the other way around. (Or it might plug in, but you will not have access to SAS functionelities)
For 40 drives, you should reconsider…
With SAS expanders in the disk shelf, you can connect all drives using a single HBA; a 9300-8e would do.
Without SAS expanders, you’ll need 40 SATA ports and the corresponding cable spaghetti.
SAS is compatible with SATA drives.
If you are going this far, buy two power supplies and assemble a power distribution board and have redundant power. Make sure each supply can carry the entire load. I did this for some network gear when the internal PS died. I also ‘stole’ power out of a Supermicro disk expansion shelf to power some external expansion chassis I had.
Once you get into doing your own power supply work you can make some serious improvements.
Only on small, non-enterprise hardware. Even SATA backplanes that do not have port multipliers will have additional functionality to report status back to the enclosure management system (BMC/IPMI).
…unless it’s a SAS expander backplane, which really would be a good idea in OP’s case.
I was orienting myself with this
As long it supports sas3 and is cheap I don’t really care.
That said I already have enough HBAs and sas expander.
It depends on the number of drives and power requirements for 5V and 12V and from my research this is what I found.
I bought a 72 drive server chassis and decided to use ATX PSUs because they are quieter (I am still looking for a quieter chassis fan cooling solution)
It has 3 x 24 drive back planes and according to WD and the 20 TB drives I was going to use, each drive requires 0.99A @ 5V and 2A @ 12V at peak operation which works out to be about 24A @ 5V and 48A @ 12V for 24 drives in each backplane. The actual power draw will probably be less because of staggered start up and not all drives being at peak operations.
So I found 3 individual ATX PSUs with these specifications for each of the 3 back planes. The 12V rail usually has an abundance of current and it is the 5V rail which is limiting factor and only a few ATX PSUs have 25A 5V rails even if the total power rating for the PSU is large eg 1000W
I believe BackBlazes uses 2 EVGA NEX750G to power their 60 drive Storage Pods 6.0 but I think they use smaller drives with lower current requirements @ 5V
That phrase certainly takes you down some weird rabbit holes. Especially given how many SATA connectors are also made by Molex.
It comes down to how suitable a given connector is to handle the given current. For a graphic illustration of that, look no further than the current sensors that Allegro Microsystems makes, with SOIC 8 packages being rated to measure 65A currents … with all that current passing through two sets of 2 legs of said SOIC8 chip. Presumably made of silver, I imagine.
What many of these SATA / MOLEX disasters likely have in common is undersized cables / cracking, high contact resistance, arcing, low contact area, or a combination thereof. That leads to heating and eventually melting / fire. It’s one reason that ensuring that contacts are clean and seated deeply/fully is so important. I like to use DeOxit to clean contacts and sometimes I even remember to apply it to HDD electrical contacts before inserting a drive.
Another nice feature for the Lian Li case I used is that it has a backplane option (which happily also only delivers +5VDC and +12VDC) and a HDD tower, which locks the drives in place, and will not lock down unless the drives are fully seated.
For the UPS I was building, I used oversized conductors, which are harder to wrangle, but which also reduce the voltage drop that each cable introduces. It is actually pretty difficult to source larger diameter wires for pre-confectioned stuff like 5.5mm x 2.1mm round connectors mated to extender cables, for example.
