How To Guide How to set up an NFS file server

How to set up an NFS file server

Fundamental to Linux is the concept of a file system, which is an area where files are stored. Even when Linux is used in an embedded system it still needs a file system. This can be held in silicon on the board (RAM, Flash or ROM) or other media (for example, floppy disks, hard disks, CDs, DVDs and others). A file system can also be accessed remotely across a network connection, and can be a combination of any of these mechanisms.

Linux supports several different file system organizations, which have different characteristics making them suitable for different applications. For example one file system may have faster access times than another, but be less efficient in how it uses the available storage space.

A file system is made available to Linux by mounting it. The new file system is then visible as a directory within an existing file system. For most purposes crossing from one file system to another is invisible to user programs. File systems can be freely mixed, so for example an ext2 file system on a hard disk can be mounted into a JFFS2 file system in Flash memory.

There must be an initial file system into which others are mounted. This is called the root file system, and is where the root directory (identified as /) resides. This is mounted by the kernel as it boots, so the first program which the system executes (init) must be read from the root file system.

For development purposes, the most convenient option is to have the root file system as a remote system accessed across the network. In this way, a directory (and all the files and directories contained in it) can be created and maintained on a disk in the host system and appear as the root file system on the target.

Remote file access uses a protocol called NFS (Network File System), and a server must be set up on the host PC to handle this protocol and enable the target system to access the files on the host.