What is a dynamically expanding disk? – Dynamically expanding disks are a type of disk which allows you to effectively use physical storage space. When you first create a dynamically expanding disk, it is small in size and only takes up the storage space that it actually needs.
A dynamically expanding disk grows when new data is added to it, thus allowing you to minimize storage costs. Moreover, dynamically expanding disks work well in testing and development environments, and are greatly compatible with servers running non-disk intensive applications.
How can you reduce the disk size? – If not monitored properly, a virtual hard disk can expand to its maximum size, thus consuming a lot of physical storage space. However, deleting files from the virtual hard disk will not resolve this issue. The only way to do this is to manually reconfigure the disk through shrinking or compacting.
When the disk has reached its maximum size, you should open the Edit Disk wizard in Hyper-V Manager and select whether you want to shrink or compact a virtual hard disk. Remember that the virtual machine (VM) should be turned off for these operations to work.
What is the difference between shrinking and compacting virtual hard disks? – When shrinking a Hyper-V disk, you reduce its maximum size limit. When compacting a Hyper-V disk, the physical disk space consumed by a virtual disk is reduced and unused physical disk space gets reclaimed.
The shrink option reduces the storage capacity of the virtual hard disk, while the compact option allows you to compact the file size of a virtual hard disk, leaving the storage capacity intact.