I rewatched Spaceinvader video and I noticed, that:
1. His Windows vdisk is in /mnt/remotes/zfs_vms/sandbox_windows_10/vdisk1.qcow2
2. There are 3 snapshots:
- Neo/vm-storage/big_sur
- Neo/vm-storage/sandbox_windows_10
- Neo/vm-storage/
When he uses Rollback, he selected "Neo/vm-storage/" and not "Neo/vm-storage/sandbox_windows_10" which means, that changes in "big_sur VM" were also reversed (if there were any).
I checked this in on my system and it works. Rollback on snapshot BACKUP_POOL/VMs restores my Manjaro.
So it looks like the vdisk has to be under another Dataset to recognize the changes, in my test example it looks like this:
Pool:
BACKUP_POOL/VMs/TEST2/TEST3
NFS share in Unraid:
nfs TRUENAS:/mnt/BACKUP_POOL/VMs/TEST2
VM vdisk location:
/mnt/remotes/TRUENAS_TEST2/TEST3/vdisk1.img
I did Snapshots and Rollback for:
BACKUP_POOL/VMs/TEST2
EDIT:
I found better solution. Instead creating additional Dataset, just create a Folder inside existing Dataset and place there the vdisk