[OpenAFS] Re: afs vs nfs

Joe Buehler jbuehler@spirentcom.com
Tue, 22 Nov 2005 08:38:31 -0500

Noel Yap wrote:

> Does anyone have an _up-to-date_ site comparing AFS and NFS? 
> Searching has turned up lots of old ones.

You seem to be getting some rather flip responses so I will chime
in with this:

- AFS has a single namespace: the content of /afs is the same on all
machines (or under whatever drive letter(s) you pick for Windows).

- AFS is an internet filesystem -- you can access other AFS sites
(under /afs like everything else) if they let you.  Location
of the foreign AFS servers via DNS is supported so this can all
be made relatively transparent.

- AFS uses Kerberos for security and is ACL-based.  Being root on
a machine doesn't automatically give you permission to do what you
want to files under /afs.  You have to have proper Kerberos tokens
for any access.  This is great if you have a software development
environment where your users need to have root.

- AFS storage is organized into volumes, attached to one or more mount
points under the /afs tree.   These volumes can be moved from server
to server while they are in use.  This is great when you have to
take down a machine, or you run out of space on it.  The users never

- AFS clients cache files.  Further, the cache algorithm is designed
to eliminate network traffic: clients do not ask the servers whether a
file has changed, the servers are responsible for telling the clients.

- AFS supports replication -- AFS volumes can have read-only replicas.
For things like binaries that don't need to change that often, you can
replicate the files to several servers after which a server failure
is automatically worked around by the AFS client machine.

- AFS comes with a backup system that is not hard to integrate into
whatever you use for backups (we use Legato here).

- AFS supports Windows.  The ability to seamlessly share files between
UNIX and Windows machines in a unified namespace is a huge feature
as far as I am concerned.

- AFS has decent support from the open-source community.  If you have
problems, there are people here who are willing to help.
Joe Buehler