I am in charge of a large computer science dept computing infrastructure. We have a variety of student and develo9pment users. If there are problems we’ll see them. We use an Ubuntu 20 server, with NVMe storage. I’ve just had to move Centos 7 and Ubuntu 18 to use NFS 4.0. We had hangs with NFS 4.1 and 4.2. Files would appear to be locked, although eventually the lock would time out. It’s too soon to be sure that moving back to NFS 4.0 will fix it. Next is either NFS 3 or disabling delegations on the server. Are there known versions of NFS that are safe to use in production for various kernel versions? The one we’re most interested in is Ubuntu 20, which can be anything from 5.4 to 5.8.
