Lately, I was working with a customer on an existing 2-nodes Storage Spaces Direct cluster (a.k.a Azure Stack HCI). The existing nodes are running on Windows Server 2019.
The customer fires up Failover Cluster Manager (FCM) and deleted a cluster volume which was created as a test volume. He switched back to the storage pool and noticed that that the free space remains the same after deleting the volume. He closed and opened FCM multiple times and noticed the same thing. Well, this is unexpected behavior.
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What is the root cause?
To find out what state cluster virtual disks are in, use the following PowerShell commands:
Get-VirtualDisk | Select-Object FriendlyName,HealthStatus, OperationalStatus, DetachedReason
As you can see, I have one disk in Detached state and the detached reason is (By Policy). The cluster virtual disk was removed from Failover Cluster Manager.
According to Microsoft description here, when the operational disk state is Detached, this means that an administrator took the virtual disk offline, or set the virtual disk to require a manual attachment, in which case you’ll have to manually attach the virtual disk every time Windows restarts. In this case, the volume was removed/deleted using Failover Cluster Manager (FCM). Therefore, the virtual disk was removed from FCM UI only but not entirely deleted yet.
Now before the virtual disk was removed, the free space in the storage pool was 12.6TB. The Free Space remains the same after the disk was removed using FCM.
We can see the same thing in PowerShell (116-104=12TB).
How to reclaim storage space after deleting a volume
To reclaim storage space after deleting a cluster virtual disk from Failover Cluster Manager (FCM) is by running the following cmdlet:
Get-VirtualDisk | ?{$_.OperationalStatus -eq “Detached”} | Select-Object FriendlyName,HealthStatus, OperationalStatus, DetachedReason | Remove-VirtualDisk
Once the Detached disk is removed, you will see the disk space is reclaimed back to the storage pool (116-84=32TB).
Conclusion
The message is clear from Microsoft. Windows Admin Center is the primary modern browser management tool that should be used to manage your environment. But for folks who used the traditional inbox management tools for quite some time, they are used to the old tools (MMC, FCM, etc.), because we are creatures of Habit. So we need to start to unlearn and remove the old habits and relearn to use the new tool ;)
As a side note, Microsoft is not investing any more in Failover Cluster Manager (FCM UI) development.
If you are using Windows Admin Center to manage your Hyper-Converged environment. The disk space will be reclaimed automatically to the Storage Pool once is deleted.
Hope this helps!
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Thank you for reading my blog.
If you have any questions or feedback, please leave a comment.
-Charbel Nemnom-
