I installed Windows Server 10 TP on my servers yesterday, I setup a brand new environment of VM's with Generation 2 as a baseline across it, Windows Server 2012 R2(1 x DC, 1 x AD CS, 1 x Exchange, 1 x SCCM 2012 R2) and Windows Server 10 Technical Preview(1 x DC + 2 x Hyper-V nodes). These all appear fine.
I also setup some new Debian Wheezy (7.4 and 7.6 mix) VM's as Generation 1 to start playing with logstash/influxdb. These disappeared after they were setup from the Hyper-V Manager on the Hyper-V node. The Hyper-V node is not domain joined and as such there is only one user account at the moment on it, of which everything was installed as.
I noticed the used memory after reboot stayed high (40%+) even with all Windows VM's powered off. Using Get-VM, I can see all the Linux VM's I installed previously. The question is why are these not appearing in the Hyper-V manager, is this to force me to learn more powershell when I use *nix systems?
Using SSH to the IP's of each VM I am able to connect to all of them, so they are running as they should underneath the covers.
I have not seen this behavior on either Windows Server 2012 or Windows Server 2012 R2 where the VM's of any sort (supported), appear properly in the Hyper-V Manager.