I have started replacing the 8 year old 2 TB drives in my backup array.  I had previously updated both parity drives to 8 TB, and am in the process of shrinking the array.  I am following the procedure outlined here:

 

https://wiki.unraid.net/index.php/Shrink_array

 

Specifically the clear drive then remove section.

 

I am using the unbalance plugin to move everything off the old drive on to the new drive, the the clear_array_drive script to clear the old drive.

 

Reading the description of what the clear_array_drive script does, I am wondering if that step is really needed.  The wiki says the script "it will completely and safely zero out the drive" Once removed these drives will be destroyed so I am not worried about data being retained on them.  Does the script do something else necessary for the procedure?  I can be patient if needed, but it would be nice to avoid another lengthy step if possible.

 

Thank you for your help.

 

Kevin

Just a moment for a quick comment, but if I understand things correctly, when you 'zero' the drive like that it allows you to preserve parity. 

Thus it may not be entirely required;

If for example you wanted to retire a bunch of drives, merge their contents onto another larger disk and then remove them - since the drives about to be retired already have the data in question, you could just essentially copy all the data from 'soon to be retired' drives to the 'new' drives. Copy, not move - then you have backup data in case anything goes wrong later. Then just recreate the array with only the new drives and rebuild parity.

If this doesn't make sense though - don't do it. 

I don't have a large array and also have full backups but I replaced 2x2tb with 2x4tb and used a similar technique as outlined above.

 

The key thing is that the clear_array_drive script allows the drive to be removed without rebuilding parity. If you're confident all your data is migrated and happy in it's new location - then it's probably not needed.

Edited October 11, 20187 yr by Delarius
clarity

That makes sense.  It's been 20 years since I studied how using parity to reconstruct data worked, but it makes sense that zeroing the drive would be a step that would preserve parity.  I was thinking that once the data was gone, parity would be intact without the drive, and I could just yank it, but I can at least conceive of how that would not be the case and you'd need to zero the drive before you could pull it and have parity stay intact.

 

Patience it is then. 🙂

 

Thank you for your time and reply.

 

Kevin

Read those instructions carefully. It's just a matter of checking - open a terminal and make sure you never clear or format a disk by mistake. List your disks and you can verify all the files came through. ls is your friend.