RN104 Adding disks incrementally

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ReadyNASinUK wrote:

 

So when I add another 1TB, it sounds relatively simple for XRAID to expand the volume to 2TB (of RAID-1); so I am wondering why this would be outside normal use for XRAID?

 

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XRAID generally will ignore the inserted disk if it is smaller than the largest installed disk in the array. In your case that is 3 TB.  Netgear expects that with XRAID is that you would now be adding 3 TB drives.  Not 1 TB.

Since you are wasting 2 TB of space, the expansion would work if the NAS attempts it.  But depending on how the initial size check is coded, it might refuse to attempt it.

I don't work for Netgear, so I don't know if the initial size check will let the expansion be attempted or not.  It might not work.  As I said, there is no harm in trying - if the disk is not added to the array you can simply remove it.

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ReadyNASinUK wrote:

 

Then, when I then take to 2x 1TB out, and replace with 1x 3TB, it would seem normal for XRAID to expand the volume to 3TB and then apply RAID as there are now 2x 3TB disk. 

 

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The problem with your plan is that your interim step prevents your final step (assuming that the interim step actually works).

XRAID has single redundancy - the ability to rebuild any single disk from the others.  When you remove two disks (as you are planning in the final step) then you immediately lose the entire volume.  All data is lost.

Also, XRAID won''t let you permanently remove disks - and you are attempting to shrink the array from 3 drives to 2.  It just won't do that.  

On the other hand, when you go from 3TB + 1TB to 3TB + 3TB, you are only removing one drive - so XRAID can restore the volume on the new disk when you insert it  After it does that, it will expand the volume to use the full 3 TB capacity.