On my Windows Server 2012 R2 I have a storage pool capacity of 2.22TB and 516GB free space, however I cannot extend my virtual disk past 1.72TB. The UI will let me create another virtual disk with the 512GB capacity but not extend into it.

storage pool layout

On my other box I can get full capacity allocated.

storage pool layout 2

How do I get it to let me extend my virtual disk into that free space?

  • Off hand I do not know, but it may be worth dropping into powershell and do a get-virtualdisk | fl of both systems, and compare item by item and see if anything relevant looks different. The GUI hides a lot from you. Seems doubtful (with two each), were both pools created initially with both physical disks present and unchanged since? Adding disks later vs initially can also create differences in structure under the covers. Same format (NTFS vs ReFS)? – Linwood Sep 18 '16 at 15:00
  • The only difference I can see bar the writecache on the other server (it's tiered with a SSD) is that It has two columns. What effect would that have on the problem? – Nicholas Krijger Sep 19 '16 at 3:53
  • I'll let someone who understands better answer but I think the answer may be yes. I'm not even sure how you can have two columns given the size of the drives, but columns affect how disks can be added, and may well affect whether files can span disks. – Linwood Sep 19 '16 at 12:36

Managed to sort my problem out by recreating the storage pool with just 1 disk, creating the virtual disk with 1 column and then adding the second disk and expanding. Would have been nice for a less destructive route but it did fix the problem, full capacity used now.

Hope this helps someone else in the future.


The two columns are the reason for this. It means, each "piece" of data in the virtual disk is "split" between the two physical drives. So when the smaller drive is used up, it can not extend beyond that. So the maximum space you can use is the size of the smaller disk (882 GB) multiplied by two (is about 1764 GB , 1.72 in TB).

A bit annoying as the column count is barely mentioned in the GUI.

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