Unlike some sites, AFS is not presently a major component of the Nevis Linux cluster. Therefore, apart from pointing to resources such as the OpenAFS documentation and the FAQ, there is no general description of AFS here. This page just discusses the implementation of AFS at Nevis.

The Nevis AFS setup might best be described as "baby AFS". AFS is not used for centralized authentication (NIS is used instead), nor is it used for distributed filesystem access (we use automount for this). We only use AFS for software that cannot function otherwise in the Nevis environment; as of May-2007, that's only the ATLAS Athena software, located in /afs/nevis.columbia.edu/athena.

Here are the general rules/policy:

• All systems that have access to the Nevis batch farm have the OpenAFS client software installed.

• If you need AFS client software to be installed on a Nevis system, just ask. Note that the system will almost certainly require a kernel update and a reboot.

• The main AFS cell of all Nevis cluster systems is nevis.columbia.edu.

• To see the files on the Nevis AFS filesystem, you can execute the following command on any system at Nevis with AFS installed: cd /afs/nevis.columbia.edu

• Only at Nevis (see below), this has been aliased so that the path /afs/nevis is equivalent to /afs/nevis.columbia.edu

• The existence of the /afs/nevis.columbia.edu filesystem has not been generally announced to the AFS community. Therefore (unlike, e.g., /afs/cern.ch) it is unlikely that systems outside of Nevis will be configured to see the Nevis AFS filesystem.

• If you'd like for an AFS system outside of Nevis to be able to access /afs/nevis.columbia.edu, you'll have ask the administrator of that system. Send them a copy of /etc/openafs/CellServDB from a Nevis system, and ask them to append the first few lines from that file (the ones that identify the nevis.columbia.edu AFS servers) to the end of their CellServDB file.

• At Nevis, the contents of /afs/nevis are not backed up. They are treated like /data partitions in the Nevis standard backup policy. None of the AFS volumes are replicated either.

• If your work requires it, a disk partition can be created and formatted for AFS, and/or an AFS account can be created to allow you to modify files in /afs/nevis.columbia.edu. However, bear in mind the policy limitations described above.

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