Challenge
Windows File Level Restore hangs on "Starting restore session" for abnormally long period of time while free disk space on drive C:\ keeps decreasing dramatically.You may find following path with cache file constantly growing:
C:\Windows\system32\config\systemprofile\AppData\Local\mount_cache{GUID} or C:\Windows\SysWOW64\config\systemprofile\AppData\Local\mount_cache{GUID}.
Cause
The issue occurs when guest Windows has Transactional NTFS (TxF) turned on. When mounting to Veeam server it can cause NTFS driver to enter infinite loop trying to re-apply transaction log.Solution
To resolve:1. Login to guest OS as administartor. Run cmd with elevated privileges. Execute 2 following commands:
fsutil resource setautoreset true
fsutil resource setavailable
2. Make a new backup point of that VM. verify that File Level Restore starts fine from new backup point
More Information
For more information about Transactional NTFS (TxF)https://msdn.microsoft.com/ru-ru/library/windows/desktop/bb968806(v=vs.85).aspx