I have five 4TB disks in a storage space (there was formerly another 3TB in here - see below).  The set-up is Pool capacity 18.1TB, Storage space size 13.9TB, Including resiliency 20.8.

The actual space used in the Dashboard/Storage/Hard Drives screen is:  Capacity 14264.4GB  Used space 4009.2GB   Free space 10255.2GB.

I am getting a "Low capacity" warning so I checked the management of the storage space and it is showing "Using 14.1TB of 18.1TB pool capacity".  The disk are showing 79.4%, 74.6%, 74.7%, 79.4%, & 79.5%.'

File explorer shows the total of "ServerFolders" at 3.53TB.

How it got here:

1. Noticed a low space warning in the Dashboard.

2. Added another pair of disks to the server and used "DrivePool" form StableBit to set them up as a redundant pool of 6TB.  This was in part to experiment with performance difference from the standard MS offering for redundancy.

3. Used the Dashboard to move the "Client Computer Backup" folder of 4.5TB to this new drive using the "Move Folder" process in the Dashboard.

4. Once the data move had taken place I shut down and re-started to ensure all was well. Looked OK so shut down again and removed one drive (3TB) from the original Storage space.  On re-start the system, as normal, recognised this missing drive and did a data rebuild.  I then used the "Remove" option from the Dashboard to get this drive out or the Storage space.  Waited for the full data rebuild, took ages as per normal.

5. Checked the result - see my opening comments - things just don't add up!

It appears the 4.5TB that was moved, along with its parity copies, is the space that has not been surrendered from the "Storage Space".  I suspect that the move process is still hanging onto the space for some reason.

What the heck is going on here!  I am currently in the process of moving out all files so I can rebuild the Storage space in empty form and start again.  Oh and I'm also going persist for a while at least with DrivePool to see if it is faster than the MS redundancy offering.  Maybe I'll stick with it!

I don't believe I should have to take such drastic steps to recover the space.  Any help out there to getting this sorted?  Oh and just in case anyone is freaking out, I have a large backup device attached from where I can recover everything plus other off-site redundant backups of all the data.

Hi,

According to your description, my understanding is that after adding new drive and removing old drive, disk usage displayed on Dashboard does not match the real usage. 

I am afraid that there might be some mistaken during the process of adding/removing drives. Backup important data and rebuild the spaces might be necessary. 

It is recommended to use built-in function on Dashboard to manage the spaces, detailed information you may reference Manage Server Storage in Windows Server Essentials:
https://technet.microsoft.com/en-us/library/dn550731.aspx

Best Regards,
Eve Wang