Suspending a virtual machine pauses operations in the virtual machine without shutting it down.
After you resume work and perform additional work in the virtual machine, you cannot return to the state that the virtual machine was in at the time you suspended it. To preserve the state of a virtual machine so that you can return to it, take a snapshot.
The speed of the suspend and resume operations depends on how much data changes while the virtual machine is running. In general, the first suspend operation takes longer than later suspend operations.
When you suspend a virtual machine, a file with the .vmss extension is created. This file contains the entire state of the virtual machine. When you resume the virtual machine, its state is restored from the .vmss file.