22.2 About NFS

A Network File System (NFS) server can share directory hierarchies in its local file systems with remote client systems over an IP-based network. After an NFS server exports a directory, NFS clients mount this directory if they have been granted permission to do so. The directory appears to the client systems as if it were a local directory. NFS centralizes storage provisioning and can improves data consistency and reliability.

Oracle Linux 7 supports the following versions of the NFS protocol:

  • NFS version 3 (NFSv3), specified in RFC 1813.

  • NFS version 4 (NFSv4), specified in RFC 7530.

  • NFS version 4 minor version 1 (NFSv4.1), specified in RFC 5661.

NFSv3 relies on Remote Procedure Call (RPC) services, which are controlled by the rpcbind service. rpcbind responds to requests for an RPC service and sets up connections for the requested service. In addition, separate services are used to handle locking and mounting protocols. Configuring a firewall to cope with the various ranges of ports that are used by all these services can be complex and error prone.

NFSv4 does not use rpcbind as the NFS server itself listens on TCP port 2049 for service requests. The mounting and locking protocols are also integrated into the NFSv4 protocol, so separate services are also not required for these protocols. These refinements mean that firewall configuration for NFSv4 is no more difficult than for a service such as HTTP.