Hello.
I've set up a NAS as an iSCSI storage unit (one LUN) and made it a CSV - it's 14.5 TB.
On the storage I've created a dynamic VHDX file at around 14.3 TB.
I've then attached the VHDX file to a VM that runs my backup software (Veeam).
When no data was on the disk the space available in Windows on the VM was almost the same as the available space on the iSCSI unit / CSV.
Recently I've been having problems with my VM pausing due to low disk space.
In Windows the drive has 8,41 TB free space of the 14,3 TB available.
In the Failover Cluster Manager the drive has 122 MB free space of the 14,3 TB available.
If I inspect the disk via the Failover Cluster Manager it says the current file size is 14,28 TB and the maximum disk size is 14,4 TB.
In explorer one of the Hyper-V hosts I can see the VHDX file is 14.2 TB.
It appears there's an inconsistency as to how much data and free space is available.
I expect it might be the VHDX file has actually been used to it's fullest potential and then the backup software has removed content according to it's retention policy leaving "space" inside the VHDX structure. Now when backing up the software writes
to the disk but the OS thinks the disk is full and puts the VM on pause mode to prevent crash. If this is correct how do I prevent this from happening? I guess it's possible to use fixed size VHDX instead but are there any other options?