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

[Cyber Akuma]

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?

 

[Silhouette]

The answers to pretty much all your questions depend on which controller (or software) you're using.

BTW my first instinct when I have a drive failure at home is to make sure my backup is uptodate before I rebuild. Create a backup of your backup too if possible. If your backup covers 90-99% then making a copy of the rest from your RAID results in a lot less drive stress than a full rebuild. So do that, then rebuild. In that way even if more drives fail you will reduce the risk of data loss.

 

[Cyber Akuma]

The answers to pretty much all your questions depend on which controller (or software) you're using.

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.

Also, another thing I 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?

 

[Silhouette]

Preferably somebody with more recent experience with LSI raid controllers will help you. My recent experience with LSI is limited to HBAs. That said, RAID controllers will keep configuration data (like "this is drive X in a raid5 with id Y consisting of N drives") on the HDDs so that the raid can be reimported if (for example) your old controller dies. Given my experience with old LSI controllers I do not think a change in the drive order will cause any problems, neither should removing the drives temporarily.

You might want to ask LSI support to be certain. Skip the part about crossflashing the controller though

 

[Cyber Akuma]

Would that import still work though if one of the drives had to be replaced?

 

[RedJamaX]

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?

Did you power it on after you put the drives in the wrong order?
Possible answers:
1. "No - I didn't want to take a chance" - Best to re-install them in the same physical order that they were originally configured in.
2. "Yes - And it failed to recognize the array" - Then, yes, you MUST have them in the exact same order
3. "Yes - And the array came up fine and I could access the data" - Then, No, your controller will identify the array regardless of physical drive order.

If so, is there any way I can tell which order the drives were originally in?

No.

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?

Refer to your manual... but... if you answered #2 above, then it will probably not work. And if you answer #3 above, then it will most likely be ok... BUT, Don;t take my word for it... refer to the manual.

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?

Refer to the manual... but, most of them auto-rebuild by default... especially the ones that do not require a specific drive order.

 

[cantalup]

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?

you should be OK!
since raid metadata were written in HD' self...
you can put not in order. I have been doing these with hardware raid starting with adaptec 3XXX series, LSI clone (IBM-Lenovo Dell version).....

The most improtant STEP!!. remember to put all HDS (in RAID), do not missing a single or more HD. It this happens.... 1 missing can be handle by RAID5, or 2 missing can be handle by RAID6.

on HBA card, need to be more carefull... I always using /dev/disk/by-id/ or /dev/disk/uuid when creating software RAID, this means I can move around all HD since by-id or uuid never change, unless you add new drive or (format the drive that wipeout uuid).