Notes on AFS

I have been using AFS (originally the Andrew File System) since 1993 and have been helping to administer Stanford's fairly large AFS cell since 1998. For those not familiar with AFS, most commonly found these days in its free software implementation OpenAFS, it is a Kerberos-authenticated enterprise file system whose primary features include Kerberos-based directory ACLs and groups, a highly scalable infrastructure suitable for huge organizations with tens of thousands of clients (or more), client-invisible file migration between servers, and replication of critical data across multiple servers. It is widely tested, highly stable, and supports every major variation of Unix as well as Mac OS X and Windows.

I have written the following white papers about how we run Stanford's AFS cell:

AFS Reporting Database

We load AFS volume metainformation nightly into a SQL database to support nightly and ad hoc reporting. This paper explains the motivations, provides the database schema, outlines the process, and discusses some of the queries that we have found useful.

AFS Server Balancing

How to phrase AFS server balancing as a linear programming problem and use a linear programming optimizer to find a good balance. Discusses the possible approaches to server balancing and an algorithm for finding a reasonable solution.

Mathematics of AFS Balancing (PDF, TeX)

A paper giving the complete mathematical statement of the linear programming problem described in the above white paper. Of interest only if you find math easier to read or more precise. A more succinct (but less pretty) statement of the same mathematics can be found in the AMPL model.

Here are slides from presentations I've given about AFS:

• AFS and PAM (PDF, TeX)
• AFS management tools (PDF, TeX)
• Daemons, PAGs, and automated authentication (PDF, TeX)
• Public Unix software tree in AFS (PDF, TeX)

You may also want to look at the AFS-related software available from my software page.