I have a linux 6.5 RHEL VM in which I am running an instance of PG 9.4. In order to test NFS, I want to run a second instance on same VM but different file system.
init the cluster on the file system you want using -D, assuming the VM can access that file system.
FYI, best practices is not to run on NFS, so do not be surprised if things break.
Has anyone done this and is it possible with no issues?
Or is it better to run different versions of PG on same server?
No, you just need to make sure the Postgres clusters are listening on different ports. That means going into postgresql.conf in the cluster and changing the port variable.