Q. Is there a problem with backing up a VM that is also replicating with Hyper-V Replica?
A. It is very common to want to replicate virtual machines for DR purposes but also still back them up. Hyper-V Replica adds a certain amount of overhead on the storage subsystem as all writes are also written to Hyper-V Replica log files. When a backup is performed there is additional overhead on the storage subsystem however a backup uses a snapshot while Hyper-V Replica uses journaling so they can co-exist with no issues however a common solution that is fully supported by Microsoft to avoid the doubling of overhead during backups is to backup the replica VM and not the source.