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Dell PERC S300 SAS Power Connections

Posted on 2016-10-21
Last Modified: 2016-11-22
Hey guys,

I'm trying to install a SAS drive from a failed RAID array so that I can run SpinRite on it (last ditch effort to recover a file from the array).  

I have a PowerEdge T110 ii with a PERC S300 controller and I'm trying to connect the SAS drive to it so I can boot the SpinRite CD and run a scan on it.  

The PERC S300 has the wiring harness in the attached pic.

My question is in reference to the two plugs on the end (P1 and P2). Do these need to be connected to provide power to the drives through the harness or does the power come from the PERC controller itself?

If they do need to be connected - do I just connect them to the SATA power plugs coming off of the power supply?  They look like they'd fit but - I'm not sure and don't want to risk frying something.  

Thanks in advance!  Happy Friday!!!!!
Question by:ttist25
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LVL 47

Assisted Solution

dlethe earned 150 total points
ID: 41854175
DONt run spinrite on a disk in a RAID array.  only way that could possibly help is if the array was RAID1, and if that was the case, you wouldn't need spinrite anyway because the data would be on the mirror.

If you want the data for a file in a busted RAID array, you're going to just have to pay for professional recovery.  Since it is a RAID array be prepared for several thousand dollars minimum.  

You could take a drive in a failed array and literally output a random number generator and fill the failed drive with that data and it wouldn't do anything more to recover your data.  (Again, assuming not RAID1).  

As such my non-answer answer to your question is ... STOP. If data is worth thousands of dollars get the disks to a professional.  Otherwise don't waste your time.

Now there are products that will reconstruct a broken RAID array, like runtime.org reconstructor, but that assumes a premise that the raid configuration itself is lost.  You probably have a working RAID config, but too many HDD errors for it to come online.  Runtime's software won't help with that.
LVL 55

Expert Comment

ID: 41854365
One of them connects to the PSU, the other provides power to the DVD as you can see here -

As dlethe says you may make it worse although if it's RAID 1 then there's a chance of seeing the data if you skip past the metadata and find the filesystem.

Author Comment

ID: 41854377
Hi dlethe!

Thanks for the response, it is greatly appreciated.  

I've resigned myself to the fact that this is probably NOT going to work and that I'm going to have to start over from scratch (had replacement disks delivered this morning).  It's not necessarily a bad thing as I've learned some things about RAID 5 and "spinning rust" since I originally setup this box.  The failed disks are from a RAID 5 array so I'm pretty much screwed.  I have an older backup of the specific file I'm trying to recover so it's not an "epic" problem but I'd still like to give it one last try before I give up.  

I have used SpinRite in the past on single drives and it was able to recover them.  I have also used it on as many drives (if not more) where it was NOT able to recover so - even on a single drive level - it's a crap shoot.  That said, there is reference to success stories on grc.com (of course right :P) about running SpinRite separately on physical disks from a failed RAID 5 array.  

The content is not worth the cost of sending it out for pro recovery but, I don't want to do something totally stupid that'll definitely destroy it either.

So my thought process is this:  
  • If I physically remove the failed drives from the production server,

  • attach them (one at a time) to a separate physical server,

  • run SpinRite and let it try to repair the disks and, if it can repair at least one,

  • stick the disks back into the production server and rebuild/boot.

Does that have even a snowball's chance in hell or is there something I'm missing (frequently the case)?  

If it does have a chance - can I connect the SAS drives one at a time to the PERC S300  in the "test" box?

Thanks again for the response and the word of caution.  "STOP" is always prudent advice when it comes to recovery!  :D
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Author Comment

ID: 41854406
Thanks for the response Andy.  

I think those are SATA drives in your picture.  My question is in reference to connecting power for SAS drives that connect to the PERC.  The SAS wiring harness has two plugs on the end (P1 and P2) I'm uploading a better image with the plugs circled.  

Thanks again for the responses!
LVL 55

Accepted Solution

andyalder earned 350 total points
ID: 41854642
Hmm, I think you are right, what you show is the SAS upgrade cable assembly, and my pic shows the default machine which comes with SATA cable assembly that plug into the mobo. Nevertheless you still need to supply power to the drives via P1 or P2, the only difference in the standard cable and the upgrade one is the data side, the power side of the cable is the same. To upgrade a SATA based T110 to SAS you buy a PERC RAID card plus the cable you show, the power is supplied via the PSU, not via the PERC.

SAS and SATA power connectors are the same on the back of the drives and they take the same voltages.
LVL 47

Expert Comment

ID: 41854658
what is the file size and the RAID5 stripe size and how many disks in the RAID, and how many failed. Assuming best case scenario and the file is contiguous on the filesystem (LOW probability), then one can do a little math to see whether recovery it is improbable, impossible, or really hard to do.  Consider that if the file is so large it spans multiple drives and even offsets on the same drive then you have to reconstruct the RAID as well.

conversely if stripe size is 128Kb and the NTFS is set for 64K and the file is 4KB  in size, one might just do a forensic recovery on raw device and not have to worry about reconstructing anything.

Author Comment

ID: 41856329
Hi Guys,

Thanks for the input Andy.  Just looking at it i assumed that's what needs to happen but I just wanted to make sure since i hadn't used it before.  

Thanks again dlethe.  The file is a 250GB .raw file and there are 8 drives - 2 failed.  I don't know what the stripe size is.  But I'm guessing with the file size forensic recovery sans reconstruction is probably out of the question?  

Thanks again to you both.
LVL 47

Expert Comment

ID: 41856499
spinrite isn't going to recover that file.  Take it to a pro and be prepared to spend $3000+, and you might get lucky.   Otherwise, give up and save yourself the  time and effort.   Sorry.

Author Closing Comment

ID: 41856862
Thanks guys.  Hope you have a great week.

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