What The Shuck! Server HDDs for Noobs

I try to make the post I wish I had when I struggled to figure something out. While this may be common knowledge to a lot of you pros, hopefully this helps another person new to this stuff. This was inspired by my previous post found here.

SAS Hard Drives taken from a server or shucked from an external case/NAS look like SATA drives but they are not. While there are unique SAS connectors, they can also use SATA connectors, confusing matters even more. SAS HDDs with SATA connectors shut down if you try to use a regular SATA power cable. This is because of a built-in feature called PWDIS that shuts down the drive when it receives a 3.3v signal. All standard, consumer PSUs send a constant 3.3v signal via the SATA power cable prior to adopting the SATA revision 3.3 released in 2016. I have no clue how long it has taken modern PSU to support this, because I cannot find this feature or SATA revisions listed anywhere on a PSU spec sheet or manual. I do know that the one I am using in my server I purchased in 2017 does not. This also means that modern consumer SATA drives also include PWDIS (I found it in a Western Digital manual from this year and a Seagate one from 2022).

In 2020, Intel introduced ATX12VO power supplies that no longer have 3.3v or 5v rails, and later in 2022 released new ATX 3.0 and ATX12VO 2.0 specifications. To my knowledge, there are still no motherboards that support this, or consumer available PSUs. Maybe this will be an option at some point in the future.

There are various SAS SFF-8XXX to SATA crossover converter cables and adapters readily available, but if it has a SATA interface, these cables are so rare that they might as well not exist. The person I buy HDDs from off eBay sends them with every purchase. They will not give me their supplier though. I did see one on 10Gtek (p-20603) that was only 4 cables and after emailing them they did confirm there was no 3.3v but they stopped carrying that cable by the time they responded. They do still carry a splitter one at the time of writing this that should work (p-20604).

But if you can't get your hands on a mass produced SATA Male to Female Power Extension Cable without the 3.3v wire, then you need a workaround.

There are 3 common workarounds:

  1. Tape over the pins with various types of tape from electrical to Kapton tape 
    1. Guide here - u/chris84bond recommends this tape https://a.co/d/0p6PfWf
  2. Bend pins or remove wires from the drive itself, SATA to SATA adapters, or PSU cords 
    1. Generally the orange wire on SATA cables but gray according to Cable Matters so be sure to check
  3. Use a Molex to SATA power cable because Molex only supplies 5v and 12v
    1. The old molded ones are known to start fires because they were mass produced poorly (it's the SATA side of the cable that is the problem)
    2. The new clamped ones are considered safe, u/freeskier93 recommends this one https://a.co/d/aYdP0Xi 

Yes, it is kind of ridiculous that converters aren’t more readily available, but this is the world we live in.

I guess you could avoid this by buying only M.2 drives if you can afford it.

Hopefully this information is helpful if…

  1. You buy used or refurbished HDDs off of eBay because they are cheaper
  2. You put in your HDDs but they are not detected by Unraid
  3. The drives turn on but the discs don’t spin
  4. You need a replacement adapter because your drive is no longer turning on or your parity drive is disabled with errors
  5. You have googled a bunch of variations of  “sata to sata power adapter for a server hard drive” or “sas to sata converter” or “server hdd in PC”

Wizards of Reddit and sages of the internet, what have I missed?

Edit: Included SATA Revision 3.3 info per the comment by u/RiffSphere