I have a two disk two-way mirror storage pool. It consists of two 2TB drives. It's at about 75% capacity and the drives are somewhat old. I'd like to replace the drives and expand the array. To be clear, what I want to do is end up with the same storage pool with two mirrored 4TB drives. The drives are internal in a tower desktop enclosure and I'd like to end up with the same arrangement. I've read this question and it seems on-point but it refers to a parity based pool.

The technique described would is:

  1. Add one new 4T drive on USB and add to the pool.
  2. Prepare one of the original 2T drives for removal.
  3. Remove the 2T drive and replace it with the second 4T drive.
  4. Prepare the other 2T drive for removal. All data should now be on the 4T drives.
  5. Remove the second 2T drive and move the first 4T drive from USB to the internal SATA port.

The other question and the docs refer to preparing an existing drive for removal. On my computer, in the physical drive section of the Manage Storage Spaces there is no option for preparing the drive for removal, only "rename". Is it possible to use the described procedure in a mirror situation? Is there another way to accomplish what I want to do?

> PS C:\Users\Elton> Get-PhysicalDisk -FriendlyName PhysicalDisk1 | Get-VirtualDisk
PS C:\Users\Elton> Get-PhysicalDisk

DeviceId FriendlyName            SerialNumber         MediaType   CanPool OperationalStatus HealthStatus Usage       Si
-------- ------------            ------------         ---------   ------- ----------------- ------------ -----       --
1        M4-CT256M4SSD1          00000000123709162E33 SSD         False   OK                Healthy      Auto-Select GB
2        Hitachi HDS5C3030BLE630 MCE9215Q0AS51W       HDD         False   OK                Healthy      Auto-Select TB
7        Seagate Backup+  Desk   NA7D0SNK             Unspecified False   OK                Healthy      Auto-Select TB
6        Seagate BUP Slim BL     NA7JAD6P             Unspecified False   OK                Healthy      Auto-Select TB
0        SanDisk SDSSDP128G      131060400181         SSD         False   OK                Healthy      Auto-Select GB
3        TOSHIBA DT01ACA200      23KMRZLAS            Unspecified False   OK                Healthy      Auto-Select TB
4        TOSHIBA DT01ACA200      23JJYEGYS            Unspecified False   OK                Healthy      Auto-Select TB

Storage Spaces Dialog


The Storage Spaces Frequently Asked Questions (FAQ) and especially the section How do I replace a physical disk? makes it clear that in order to replace a disk you need the following:

  • The storage space must be resilient and healthy (not a simple space). Running the following command should find that ResiliencySettingName is either Mirror or Parity and HealthStatus is Healthy:

    Get-PhysicalDisk -FriendlyName PhysicalDisk1 | Get-VirtualDisk
  • There is enough space on the other disk to contain the data on the replaced disk. If there isn't enough space, you need to add a new disk before retiring that disk, even just a temporary external USB disk (but this will be slow). You can check unused disks capacity by subtracting AllocatedSize from Size reported by the Get-PhysicalDisk command.

In your case, apparently the above two conditions are not fulfilled, so "Prepare for removal" is not available.

For more information about removing a drive, with screenshots, see:
How to Remove Drive from Storage Pool for Storage Spaces in Windows 10.

| improve this answer | |
  • Get-PhysicalDisk -FriendlyName PhysicalDisk1 | Get-VirtualDisk Didn't return any output. Get-PhysicalDisk Showed the drives (output is too long and doesn't format well) Device ID's are 3,4, and both show healthy. This is a two-way mirror, so that would be resilient, yes? – Elton Dec 31 '18 at 21:33
  • I've edited the original question to show the PS data and a screen shot. – Elton Dec 31 '18 at 21:40
  • Try Get-PhysicalDisk | Get-VirtualDisk, but based on your input I think my above second point applies here. – harrymc Dec 31 '18 at 22:08

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