https://wiki.fogproject.org/wiki/index.php?title=Troubleshoot_NFS
Creating & verifying .mntcheck files
.mntcheck is a hidden and empty file that a FOG client uses during image capture and image download/deployment to verify an NFS share is mounted correctly.
To create these files, on the FOG server:
touch /images/.mntcheck
touch /images/dev/.mntcheck
Verify these files with:
ls -laR /images | grep .mntcheck