What is AFS?

AFS (short for Andrew File System) is a distributed filesystem product. It is an online disk storage system employed by universities, research institutions, and similar groups around the world for organizing and maintaining computer data. It offers a client-server architecture for federated file sharing and replicated read-only content distribution, providing location independence, scalability, security, and transparent migration capabilities. AFS is available for a broad range of heterogeneous systems including UNIX, Linux, MacOS X, and Microsoft Windows.

Why AFS?

Advantages of AFS

• Better Networking Performance: AFS was designed for larger networks so it's faster and more efficient. Under AFS, files are maintained by a central server. Client machines cache files they access to the local disk. If a client machine updates a file, it updates a local copy and sends the update to the server. In contrast, other file systems (such as NFS), require that filing systems be synchronized; this is not feasible across a large network connected by routers. And while many other filing systems work well on small and medium size networks, most are not suited for a large network like UMDNJ's.
• User Authentication: RWJMS AFS system authenticates users through CORE domain (Active Directory). This allows people with a CORE account to access their AFS space from any machine that mounts the AFS filing system.
• Easier Administration: Since AFS is a distributed system, administrators can focus on servers instead of client machines because client machines get all their information from the servers anyway. This makes updating and maintaining software much easier.
• File Permissions: AFS allows greater control over the file permissions of one's directories. Privileges can be granted to individuals or user-created groups. This is ideal for group projects. AFS users need to learn a new set of commands and file permissions that are different from those they may have used in NFS. One important distinction: AFS does not support file-based permissions; AFS permissions only apply to directories (though Unix file permissions still exist for files). AFS permissions are covered in the Permissions section of AFS Client Document.
• Backups: Each night, the AFS server creates a backup of your account which you can access. This allows users to modify files that may have been accidently deleted or overwrote.
• And last but not least, Security: AFS combined with Kerberos offers excellent security because it authenticates users and jobs, not machines (this reduces the possibility of IP spoofing). It also offers encryption through Kerberos, thus helping to reduce the chances of someone sniffing your password out of packets.

Disadvantages of AFS

AFS does not use Unix file semantics: it only supports directory permissions. This may confuse people accustomed to the standard Unix chmod permission sets. However, you will soon find that typing fs setacl ~/Public system:anyuser rl is as easy as typing chmod 755 ~/Public.