Can we add a Linux partition on a drive containing a Windows 10 storage pool?

Question

About a year ago we had set up a Windows 10 pro machine with a 250 GB SSD and a 3 TB hard drive using the defaults from the installer.

The plan was to leave 1 TB unpartitioned for later use in Ubuntu. However for reasons obscure to me Windows 10 did not create an NTFS partition. Instead it had created a single 2 TB "storage space/storage pool" on that drive which of course can not be accessed by Ubuntu. The partition table is GPT.

From Ubuntu gparted all of the 3 TB of the drive shows as used up with an "unknown file system" for such a storage pool (German locale "Speicherpool"):

The Windows partition manager only sees the 2 TB "DATEN" pool. It appears to be unaware of another 1 TB of unused space on drive 2 (drive 1 holds Windows 10 and Ubuntu).

We can see all of the drive in the storage pool settings where it is aware of the 2,72 TB provided by the drive:

It appears that Windows had grabbed the whole drive when we wanted to give it a partition only. I understand that I could probably grow the pool to the maximum size of 2,7 TB but this would no help me in providing storage to Ubuntu. I also understand that we may not be able to shrink it later.

Is there any solution for this? Is it possible that we add an extra Ubuntu-accessible partition to the unused section of this drive?

Answer 1

No, we can not add a partition to a drive that is part of a storage pool.

Storage pools on storage spaces are for providing a pool of hard drives to the OS. The purpose of this concept is to have an easy way to replace a failing hard drive or to add another drive in case of low memory in a server. Of course this approach would be rather useless in a desktop computer where only one physical hard drive sits next to the drive holding the OS.

The whole concept of storage spaces is oriented to physical drives rather than partitions. This also is why we can only add or remove a whole physical drive to a storage pool. Also because of this we can not have more than one partition on a drive that was a member of a storage pool. This partition can not be read from another OS.

To be able to use the drive with a traditional partitioning, and to add a partition that can be read from Linux we had to perform the following steps:

• Warning: removing a drive from a storage space will irreversibly delete all data on it. To date there is no known way to recover them.

• Made a backup of all files on the storage pool to an external drive.

• remove that drive from the storage pool. The graphic storage space manager would not let us do this with error "Access is Denied" 0x00000005. It could however be done from an elevated powershell with this command:

  Remove-StoragePool -FriendlyName "<Name>" 
  

• Only after that we could also remove the physical drive from the storage space.

• We then used the disk partitioner to create an NTFS partition using only a part of the drive and left some unpartitioned space for later use in Linux.
• In Linux gparted was used to create an ext4 partition on that unpartitioned space but we were also able to mount and access the newly created NTFS partition.
• We then restored the content from the backup to the NTFS partition.

Of course steps above can only be done if the storage space was used for user data only. It can not be done if Windows or part of it was stored on that storage space.