Hyper-v backup

Cannot backup Hyper_v machines on Windows 2008 R2 cluster host.

Solution:

hklm\software\microsoft\windowsNT\currentversion\spp
created the reg_Multi_SZ DisabledWriters
value = {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
net stop wbengine && net start wbengine