AFS File Service am DESY

table of contents


The DESY cell has been in operation for many years; initially running the Transarc Inc. software, which was later bought and developed by IBM, Pittsburgh Labs.
In December 2002, this software was replaced by the Open Source edition of AFS. This version has seen rapid development after IBM's decision to abandon the commercial support of the Andrew File System.

DESY Hamburg runs a cell with approximately 10 TB of disk space, 4500 registered users and some 9500 volumes.

A description of the DESY Zeuthen setup can be found here


An AFS cell is fully described on the client side by the so called database servers; these servers are the first place a client connects to in order to access files in AFS.

On Unix (DL3/4, Solaris, HPUX, AIX, SGI) systems, this configuration is held in

application/octet-stream /usr/vice/etc/ThisCell (8Bytes)
tells the client daemon which cell the client should connect to by default.
application/octet-stream /usr/vice/etc/CellServDB (30KB)
holds the information on the database servers for all cells. DESY Hamburg currently has three database servers: solar00, afsdb2 and afsdb3
This configuration file is being phased out, as the newer AFS clients are capable of looking up the cell info by DNS
Try host -t AFSDB to see the currently configured database servers.
application/octet-stream /etc/krb.conf (216Bytes)
tells the client side utilities which KerberosIV KDC to talk to.
This configuration is also being phased out, as all current AFS clients have the more secure KerberosV protocol enabled. KerberosV config information is also derived from DNS by the client utilities.

For correct operations the client daemon also needs some local configuration information:

application/octet-stream /usr/vice/etc/cacheinfo (23Bytes)
declares which mount point AFS is connected to (/afs), in what filesystem partition the AFS client side cache is written (/afscache) and what size it has.


On different platforms these files are found in varying locations; for ease of use the Windows client provides a GUI which is installed with the client side service daemon. The socalled Freelance code in the client also allows for cell discovery and automounting, so that maintaining the CellServDB file is no longer neccessary.

current configuration changes in cell

On account of cell restructuring measures the cell configuration for has changed. If you have configured your AFS client by yourself, please take note of the following new definitions for the CellServDB file on your computer: #Deutsches Elektronen-Synchrotron

You may also delete these entries from the CellServDB file alltogether, as this information is also available to your client automatically via DNS. If you do so on < 1.4.0 client machines, please add the following arguments to your afsd startup options: ¨-afsdb -dynroot -fakestat¨

Performance tuning for large files

If you use your client to work on large files O(1MB), you may see performance improvements if you add ¨-chunksize 20¨ to your afsd startup options. Please make sure that your cache partition is sufficiently sized to hold many chunks of 1 MB (> 200MB partition size)

Automated configuration updates

On IT supported Unix machines the DESY configuration is checked & updated via SALAD – there is no reason to change any parameters on these machines; it is even certain that that changes will be overwritten in the next SALAD run.
On Windows, this mechanism is not deployed under NetInstall due to agreements reached in the Windows User Meetings.