Do you need to put the drives back in the same order to rebuild a RAID5?
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Thread: Do you need to put the drives back in the same order to rebuild a RAID5?

  1. #1
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    Question Do you need to put the drives back in the same order to rebuild a RAID5?

    Ok, so I have a RAID5 made out of 4 disks, with one of the drives failing. I do have a backup of pretty much 99% of the data (that last 1% is just data I can re-download) but I am worried about Murphy's Law rearing it's head and even my backup going bad somehow, so I would really rather rebuild the RAID just to be safe instead of use the backup.

    So, I took the drives out one by one and ran SMART and read tests on them to try to see which one had failed, and it was 4th drive, I am RMA-ing it tomorrow morning. Thing is, while I was testing them, I got the first and second drives mixed up. Does it matter which order I plug the drives back into the RAID? If so, is there any way I can tell which order the drives were originally in?

    Also, I realized I was using ports 5-8 on my card, instead of ports 1-4 (The card has two Mini-SAS ports, and I was using a Mini-SAS to 4 SATA port adapter), would it cause issues if I moved them to ports 1-4?

    And finally.... do I have to issue some kind of special command or something to my RAID card to rebuild the RAID, or is it an automatic process?
    "A train station is where a train stops. A bus station is where a bus stops. On my desk I have a workstation..." - William Faulkner

  2. #2
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    http://www.recover-raid.com/failed-RAID-help.html

    Does it matter which order I plug the drives back into the RAID? If so, is there any way I can tell which order the drives were originally in?
    YES. Do NOT change positions of the drives and do not move them to different ports. I'm guessing all drives are the same make/model. If you didn't document their original positions, then I'm not sure how you would determine their order.

    And finally.... do I have to issue some kind of special command or something to my RAID card to rebuild the RAID, or is it an automatic process?
    It probably wouldn't be automatic, since you are replacing a drive. You would need to add/activate the new drive to the array. You didn't say what RAID controller you are using. You'd need to look up the manufacturer's documentation.

  3. #3
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    Quote Originally Posted by Midknyte View Post
    http://www.recover-raid.com/failed-RAID-help.html
    You didn't say what RAID controller you are using. You'd need to look up the manufacturer's documentation.
    It was originally an IBM ServeRAID M5014, which from what I was told is just a re-branded LSI MegaRAID 9260-8i, so I re-flashed it back to a LSI MegaRAID 9260-8i card long ago. It's running the latest LSI firmware, which was released Oct 21, 2014.

    I looked though it's manual but couldn't find any mention of if you can or can not change the order of the drives. I was reading up and there were forum posts about some cards being able to detect the drive itself and adjust if it physically changed to a different port, but not all cards can do that. Those posts were from 2009 though.

    Also, another thing I just realized. Was it a stupid move to power on my system with the card, but with the drives disconnected? The drive complains during the POST that all the drives from the previous configurations are gone.... is my configuration toast now or will it still remember it when I plug my drives back in?
    "A train station is where a train stops. A bus station is where a bus stops. On my desk I have a workstation..." - William Faulkner

  4. #4
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    Also, another thing I just realized. Was it a stupid move to power on my system with the card, but with the drives disconnected? The drive complains during the POST that all the drives from the previous configurations are gone.... is my configuration toast now or will it still remember it when I plug my drives back in?
    You probably shouldn't have done that. I've never dealt with that particular card before, so it's hard to say.

    At this point, your best bet is to create a new array when you get the replacement drive and restore from backup.

  5. #5
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    This would also be your chance to move to ports 1-4 and document the position of each drive (Make/model/SN).

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