Describe the Network File System and Network File Services

When stand-alone computers ruled the computer industry, users shared files with 8-inch floppy disks or cassette tapes.
When the hardware and protocol for networking computers became available, users needed a convenient way to transfer files and share resources among computers. The first mechanism to transfer files was FTP^[1], but using it was cumbersome: users paused their session, moved some files with the FTP client, and then resumed their session.

A Network File System (NFS) and a non-network File System differ primarily in how they are accessed and managed:

1. Network File System (NFS):
   • Access Over Network: NFS allows files to be accessed over a network, enabling users to work with files as if they were on a local drive, even though they are stored on a remote server.
   • File Sharing: It facilitates file sharing among multiple users and systems across a network. Users on different machines can access and share the same files concurrently.
   • Centralized Storage: Files are stored on a centralized server, making it easier to manage backups, security, and access controls.
   • Protocol-Based: NFS uses specific network protocols (like NFS protocol, SMB/CIFS) to manage file access over a network.
2. Non-Network File System (Local File System):
   • Local Access: Non-network file systems are typically used for accessing files stored on local storage devices, such as hard drives, SSDs, or external USB drives.
   • No Network Dependency: Files are accessed directly from the storage device attached to the local computer, with no need for a network connection.
   • Limited to One User/System: Usually, only the user of the system on which the storage device is attached can access the files. There's no built-in mechanism for sharing files over a network.
   • Examples: Common examples include ext4, NTFS, HFS+, FAT32, which are used by Linux, Windows, and macOS systems respectively.

Summary:

• NFS is designed for accessing and sharing files over a network, making it suitable for environments where multiple users or systems need to access the same data from different locations.
• Non-network file systems are designed for local access on a single machine, without the need for network capabilities or multi-user access.

Enter the Network File System or NFS. NFS allows users to manipulate files on a remote computer as if they were local. NFS transparently supports the usual file operations, including:

1. copy (cp)
2. move (mv)
3. delete (rm)
4. link (ln)
5. list (ls)

NFS frees users from the inconveniences of FTP. A user can access and modify files anywhere on the network using the standard command-line programs.

NFS operates using the common client-server model. NFS servers can export entire filesystems, optionally making them publicly available and NFS clients then mount the exported filesystems.
Once mounted, the server's remote filesystem is attached to the client's local filesystem.
When any file modifications on the NFS filesystem occur, the NFS client sends the modifications to the NFS server for processing.
Client-server model: A computer design model, where servers offer up one or more services for client use.
The next lesson discusses the relationship between NFS and remote procedure calls.

[1] File Transfer Protocol (FTP): FTP is one way to move a file from computer to computer.