How to move a virtual disk's physical allocation within a Storage Pool

Question

I have a pool of 3x500GB where one the physical drives is having intermittent issues. Currently, there is only one parity Virtual Disk of 300GB Fixed across 3 columns. I want to replace the bad drive with a good one. The old way (pre-2012) was replace the
disk, repair the RAID 5, resync and done. These basic steps are not working.
So far I have added a 4th 500GB drive to the pool. After searching and failing to find a way to move the data non-destructively, I decided to just pull the data cable on the disk I wanted to replace. After refresh/rescan, the disconnected drive shows "lost
communication" and the virtual disk (after trying to repair) shows "unknown" (but the volume on that disk is accessible in Explorer).  When I try to remove the physical disk in Server Manager, I get "The selected physical disk cannot
be removed". Reading the error message, I see that the replacement disk cannot contain any part of a virtual disk. The replacement disk that I just added appears to have some space allocated (possibly because I have tried this same procedure a couple
of times already?). When I look at the parity disk properties/health, it shows all four physical disks under "physical disks in use".
I have deleted and recreated a lot of storage pools lately while trying to understand how they work but I would like to avoid that this time. The data on the virtual disk in question is highly deduplicated and it took quite a while to get it that way. Since
I can't find a way to copy/mirror the disk while keeping it fully deduplicated, I would need 3x the space to copy it all off, or a lot of time to load up and deduplicate a new virtual disk.
I have several questions:
1. How can a 3 column parity disk use parts of four physical disks? And can that be fixed without recreating the virtual disk?
2. When creating a virtual disk (for example a 3 column disk in a pool that has four or more physical drives), is there a way to specify which physical disks to use?
3. I understand that after a physical disk failure, the recovery process will move a virtual disk's allocation to a replacement disk, but can a virtual disk's allocation be moved manually among physical disks within the same storage pool
using a PS script?
4. Can a deduplicated virtual disk be moved/mirrored/backed up without expanding the data?
Any help is appreciated.

Answer 1

Im still fighting with storage pools and need more tests to be done and have a lot of questions my self but ther goes what I understood so far.
You may define physical disks used for virtual disk by Powershell ,
for list of all commands follow this:
http://technet.microsoft.com/en-us/library/hh848705(v=wps.620).aspx ,
specific command defining physical disks to be used on already existing virtual disk:
Example 4: Manually assigning physical disks to a virtual disk
This example gets two physical disks that have already been added to the storage pool and designated as ManualSelect disks,
PhysicalDisk3 and PhysicalDisk4, and assigns them to the virtual disk
UserData.
PS C:\> Add-PhysicalDisk –VirtualDiskFriendlyName UserData –PhysicalDisks (Get-PhysicalDisk -FriendlyName PhysicalDisk3, PhysicalDisk4)
http://technet.microsoft.com/en-us/library/hh848702(v=wps.620).aspx
If You haven't seen this yet You may check it out http://blogs.technet.com/b/yungchou/archive/2011/12/06/free-ebooks.aspx