So, I have under the KVM host settings to create machines under a volume group. That volume group currently has 71 out of 930GB used. So, obviously, lots of space.
So, I go to create a new KVM system. In disk space for system, I put 50GB with a 8GB swap file. Location for disk image I leave at host default,, though I have also tried it with LVM. I click create, and it says:
Failed to create system : Host system host12.mydomainhidden.com cannot be used : An extra 40.73 GB free disk space is needed to create this system.
I suspect it is not checking the volume group since there is tons of space there, and, instead, checking the root filesystem or something like that. It should not be since this should be able to be created. So, I guess the workaround is to waste space by allocating it to the host system, though the space will never be used. However, this seems to be a bug to me unless I misunderstand something.