How to remove a drive in dual parity system


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I have a drive that is throwing multiple errors and probably needs replaced.  I also had included in the array but now want to replace it with an unassigned device because it will be used solely for CCTV recording ala spaceinvader video recommendations (not slowing array, no excess wear on parity disks given constant writes).

 

Since I have dual parity on my system, can I just remove the drive and rebuild parity?  I'm not really sure, but it seems WAY to complicated to do such a simple task as remove a drive.  Unraid really should have a checkbox on a drive saying 'remove this from array' 

 

I've seen some guides and FAQ but they all talk about no parity as soon as you remove a drive, but since I have dual parity I'm not sure that is true in this case.

 

Appreciate any help.

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38 minutes ago, Ystebad said:

I have a drive that is throwing multiple errors and probably needs replaced.  I also had included in the array but now want to replace it with an unassigned device because it will be used solely for CCTV recording ala spaceinvader video recommendations (not slowing array, no excess wear on parity disks given constant writes).

 

Since I have dual parity on my system, can I just remove the drive and rebuild parity?  I'm not really sure, but it seems WAY to complicated to do such a simple task as remove a drive.  Unraid really should have a checkbox on a drive saying 'remove this from array' 

 

I've seen some guides and FAQ but they all talk about no parity as soon as you remove a drive, but since I have dual parity I'm not sure that is true in this case.

 

Appreciate any help.


any time you remove a drive you will need to rebuild parity as the contents of a parity drive is calculated using ALL the data drives, so removing one means a component of the parity calculation is missing.     Having dual parity makes no difference as the same principle applies but using a different calculation for the second parity drive.

 

 

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I really miss raid6. When this happened I would just yank a drive replace it and it was back to normal. 
 

during an unraid parity rebuild on a dual parity array let’s say a second drive fails - all my data would still be correct if I added back two drives and rebuilt right?  
 

I assume that the parity drives don’t stop doing their job during a rebuild, especially given it takes about 2 -days- for my array to do the parity. 

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20 hours ago, Ystebad said:

I really miss raid6. When this happened I would just yank a drive replace it and it was back to normal. 

Removing a drive from the array is what makes this different. If you just replaced the failed drive there wouldn't be an issue.

20 hours ago, Ystebad said:

during an unraid parity rebuild on a dual parity array let’s say a second drive fails - all my data would still be correct if I added back two drives and rebuilt right?

If you were replacing a drive by rebuilding on a new drive, yes, that's what would happen.

 

If you are rebuilding parity from scratch because you totally removed a slot assignment instead of rebuilding to a drive, then no, parity isn't valid until it completes.

 

Replacing and rebuilding is totally different from removing a drive from the parity array.

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