Overview of NFS

• Developed by Sun Microsystems 1984
• Independent of operating system, network, and transport protocols.
• Available on many platforms including:
  • Linux, Windows, OS/2, MVS, VMS, AIX, HP-UX….

Unix distributed filesystems are used to:

• Centralize administration of disks
• Provide transparent file sharing across a network

The main systems are:

• NFS: Network File Systems developed by Sun Microsystems 1984
• AFS: Andrew Filesystem developed by Carnegie-Mellon University

Unix NFS packages usually include client and server components

• A DFS server shares local files on the network
• A DFS client mounts shared files locally
• a Unix system can be a client, server or both depending on which commands are executed

Can be fast in comparison to many other DFS

• Very little overhead
• Simple and stable protocols
• Based on RPC (The R family and S family) 

Restrictions of NFS

• Stateless open architecture
• Unix filesystem semantics not guaranteed
• No access to remote special files (devices, etc.)

Restricted locking

• File locking is implemented through a separate lock daemon
• Industry standard is currently nfsV3 as default in
  • RedHat, SuSE, OpenBSD, FreeBSD, Slackware, Solaris, HP-UX, Gentoo
• Kernel NFS or UserSpace NFS