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STANFORD UNIVERSITY

INFORMATION TECHNOLOGY SERVICES

IT Services Course Support

Disk Space

IT Services Course Support includes 500MB of space for you to store and share syllabi, web files, course outlines, problem sets, notes, essays, etc. Your class space is located in the University’s AFS distributed file system. Along with serving as a data storage, file sharing, and Web hosting environment, AFS enables cooperating hosts (clients and servers) to efficiently share file system resources across both local area and wide are networks. All of the materials you store in AFS are backed up regularly by IT Services. Your space is located and named according to a straightforward labeling system and file structure, making it easy to find and work with. (Example: /afs/ir/class/<name of your class here>.)

If the standard 500MB isn’t adequate for your class directory, you can request more when you register or via email to courses@stanford.edu. You can also request that IT Services allocate additional space to your students’ personal directories to accommodate assignments or other work they may need to share with you or their classmates. Just look for the additional space options on the Registration/Renewal Form or send an email request to courses@stanford.edu.

What happens to my stored data when the course is over?

If you happen to be teaching the same course the subsequent quarter and want your materials to stay in place, then you’ll need to renew the course registration using the same form you used to register the course initially. If you are not teaching the class in the subsequent quarter, you don’t need to do a thing: the contents of the class directory are archived automatically at the end of the term.

AFS Class Archive Details

Background

AFS is a distributed file system based on client/server architecture. AFS joins together multiple server machine file systems. An AFS cell is grouping of client/server machines which is administered by a domain. Stanford’s administrative domain is named “ir.stanford.edu” — which at Stanford can be abbreviated to just “ir.” Directories and files relevant to the classes you’re teaching or have taught in the past are stored under /afs/ir/class/archive. You can learn more about AFS and how it’s organized by visiting afs.stanford.edu.

AFS Storage

Your AFS storage space is divided into volumes, each of which contains a set of related directories and file. People access these volumes via “mount points”: special file elements that indicate which volumes should be associated with which directories. Volumes can be placed anywhere in AFS by using a mount point, and will then appear as a directory. For example, the files for the class EE118 taught in 2003 exist in a volume named class.ee118.1034. To access these files through AFS, that volume is mounted. Typically a mount point would created at /afs/ir/class/ee182. Under that directory will be the contents of the class.ee182.1032 volume.

How It Works

In AFS, Stanford's class directories can be found under:

/afs/ir/class/archive/

and are further subdivided, by volume, as follows:

subject/subjectnumber/subjectnumber.qtr

For example, class materials for Computer Science 147b, which is offered during autumn quarter of 2004-2005, can be accessed by the following mount point:

/afs/ir/class/archive/cs/cs147b/cs147b.1052

(The number 1052 is the PeopleSoft code for autumn 2004-2005.) In addition to the above mount point, an additional mount point for the currently active quarter is created under /afs/ir/class. In this case, there would be an additional mount point at /afs/ir/class/cs147b. These are just two mount points, two names, for the same volume and the same files; the contents of the directories:

/afs/ir/class/archive/cs/cs147b/cs147b.1052

and

/afs/ir/class/cs147b

would be absolutely identical, changes made in one location would be automatically reflected in the other location.

How Materials are Retained Year After Year

When a new quarter begins, at your request, a class system administrator will create a new volume. That volume can be a clone of the old volume or an empty volume. Using the example above, where the PeopleSoft code for winter is 1054, this material would then be found under /afs/ir/class/archive/cs/cs147b/cs147b.1054. The mount point for /afs/ir/class/cs147b is moved to point to the new volume. No class materials are deleted or moved. Only the mount points are moved. “Archiving,” then, is really just a process of moving mount points and is typically done quarterly. In addition to the above process, a nightly backup is performed on all volumes in AFS. For more information on AFS, please see afs.stanford.edu.

Last modified Monday, 03-Nov-2008 03:52:45 PM

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