Hi,
You need to check a number of things in the VM (which is getting saved during backup):
1. Integration services are installed and running.
2. All Windows volumes in the VM are formatted using NTFS.
3. There are no dynamic disks in the VM.
4. There is at least 300 MB free space available on each Windows volume in the VM.
5. There are no offline volumes in the VM.
6. Type command 'vssadmin list shadowstorage' in the VM. Verify that each Windows volume in the VM has a shadow copy storage association.
If any of the above conditions is not met, Hyper-V writer decides to save the VM during backup. It does not log the reason for doing a saved state backup. So none of the SMHV or Windows logs will show us the reason. We must login to the VM and check for each of the above issues manually.
If you want SMHV to fail the backup if VMs will be backed up using saved state, you can uncheck the "Allow saved state backup" dataset policy.
Thanks,
Anagha