Shrinking the Array Question

[TODDLT]

I have used the procedure outlined here https://wiki.unraid.net/Shrink_array#Procedure_2 to remove the last drive from my array and it worked fine. 

 

My question is if I want to remove (shrink) my array by one of the middle drives, what do I do at step 13?  For example if I was removing drive in an array of 9 drives:  

• Do I assigned drives 7, 8, 9 in positions 6, 7, 8?  
• Do I leave drive 6 blank and leave 7, 8, 9 as they were assigned?
• Or am i missing something?

 

Thanks.

[itimpi]

3 hours ago, TODDLT said:

I have used the procedure outlined here https://wiki.unraid.net/Shrink_array#Procedure_2 to remove the last drive from my array and it worked fine. 

 

My question is if I want to remove (shrink) my array by one of the middle drives, what do I do at step 13?  For example if I was removing drive in an array of 9 drives:  

• Do I assigned drives 7, 8, 9 in positions 6, 7, 8?  
• Do I leave drive 6 blank and leave 7, 8, 9 as they were assigned?
• Or am i missing something?

 

Thanks.

It depends on whether you have single or dual parity.    If you only have parity1 then you can re-order drives without affecting parity so you can (optionally) reassign them to remove any gaps.   However if you have parity2 you cannot reorder any drives without invalidating parity2 as that uses the disk slot number as part of the calculation.

[TODDLT]

7 hours ago, itimpi said:

It depends on whether you have single or dual parity.    If you only have parity1 then you can re-order drives without affecting parity so you can (optionally) reassign them to remove any gaps.   However if you have parity2 you cannot reorder any drives without invalidating parity2 as that uses the disk slot number as part of the calculation.

 

I do use 2 disk parity.

 

So, the procedure for Shrinking the array does not work for 2 disk parity except when you are taking the last drive off, correct?  The only way to do this would be to set a new configuration and re-create parity leaving me unprotected for that time?

 

Just making sure I have the situation correct.

 

 

[itimpi]

1 minute ago, TODDLT said:

So, the procedure for Shrinking the array does not work for 2 disk parity except when you are taking the last drive off, correct?  The only way to do this would be to set a new configuration and re-create parity leaving me unprotected for that time?

The procedure works for removing the drive even with Dual Purity as long as you do not subsequently reorder the remaining drives.

[TODDLT]

8 minutes ago, itimpi said:

The procedure works for removing the drive even with Dual Purity as long as you do not subsequently reorder the remaining drives.

 

So does it work to leave "Drive 6" unpopulated while "Drives 7,8,9" are populated?

[itimpi]

3 minutes ago, TODDLT said:

 

So does it work to leave "Drive 6" unpopulated while "Drives 7,8,9" are populated?

Yes.  Unraid is quite happy for you leave intermediate slots unpopulated.

[trurl]

Really simpler to just use Procedure 1 and rebuild both parity

[TODDLT]

1 hour ago, itimpi said:

Yes.  Unraid is quite happy for you leave intermediate slots unpopulated.

Thanks for taking the time to explain.  All clear now.

[TODDLT]

45 minutes ago, trurl said:

Really simpler to just use Procedure 1 and rebuild both parity

 

yes, certainly easier.  Not sure which way I will end up doing it yet.  

 

Option 1, replace 1 - 3 TB drive with a 6 - move data from another 3 TB  over to the new 6 and then drop the empty 3 TB out of the array.  No added capacity (not needed currently), replaces my last older drive, and the entire array is 6 TB drives.  This leaves me 2 open drive bays in the server to add 12 TB more in the future before I'd have to ever upgrade my parity drives and I can't even imagine how far out we'd be talking before it had to grow beyond there.  I'm pretty sure I'd be replacing the server by the time I consumed that much capacity.  I just would need to decide if I'm going to re-build parity or have an empty drive number in the sequence.

 

Option 2, replace both 3 TB wtih 6's.  Adds 6 TB capacity now and none of the other gyrations data moves and parity upgrades required (other than normal drive replacement). 

[JonathanM]

3 hours ago, TODDLT said:

Option 2, replace both 3 TB wtih 6's.  Adds 6 TB capacity now and none of the other gyrations data moves and parity upgrades required (other than normal drive replacement). 

Much safer for your data, as the removed drives will be a copy, and much less chance of user error causing data loss.