I'm having an issue backing up a few guest vm's in our Hyper-V infrastructure. We are running Server 2008 R2 SP1 on the host side. The vm's that we are having issues with are all server 2012 R2 guests. The vm's are on different clusters and hosts. Some even standalone. We're using netapp SnapManager for Hyper-V as our backup solution. Thus is basically a vss aware backup solution. The software can only backup up the 2012 r2 servers via saved state instead of online. When I run diskshadow and list writers it shows saved state instead of child partition for the 2012 r2 servers. I'm trying to find documentation on if server 2012 r2 is a viable guest os on 2008 r2 but can't find anything conclusive. My only thought some kind of issue with integration services between host os and guest os. On 2012 r2 host os I have no issues with newly created vm's. I haven't tried moving the vm's with this issue to our 2012 r2 cluster yet go see if the issue persists.
I also have a windows 2003 r2 I believe that was working and has stopped with the same issue. A reboot sometimes fixes the issue. I suspect a performance issue on the gues vm's since when I run vss admin list writers it can take as long as 5-10 minutes for results to come back. This may be the reason with this server.