A Brief Introduction to Storage on GL
DoIT provides disk storage services via the Andrew File System (AFS), a product of IBM/Transarc. The current architectures supporting access to AFS (at UMBC) are:
- Solaris (SPARC and INTEL)
- Linux (INTEL ONLY)
Other architectures are supported by AFS, but are not actively supported by DoIT. If you would wish further information on the availability of AFS client software for use at UMBC, please contact DoIT. The AFS client is available for Windows and Mac OS X.
What is AFS?
AFS is a distributed network filesystem. Data is stored on volumes, which can be physically located on any fileserver, the locations of which are known to the database servers. While traversing through a volume, one can hit mount points, which are references to another volume — the location of which may be on the same, or different server. The traversal of these mount points, and the location of file storage, is transparent to the user.
Authentication is done through the possession of tokens, which are derived upon login from the user's kerberos tickets. These tokens are kept in the kernel of the client machine, and are presented to a fileserver during file access, to verify the requestor's idenity.
Your Home in AFS
Every user account is assigned a home volume in our AFS filesystem, which contains their home directory and web space. By default, each home volume has a 100 MByte quota assigned to it. Home volumes are typically mounted within the AFS filespace in the following location:
where x and y are the first and second characters in a user's account name.
Within every user's account, the following directories exist
- home – User's data files, and UNIX home directory
- pub – User's web space, and other "public" data
- backup – Mount of the user's backup volume
Within the home directory, you'll find the trappings of a typical UNIX environment (.cshrc, .login, etc).
A typical pub directory contains a www sub-directory, which contains files to be accessed through the URL http://userpages.umbc.edu/~username.
The backup directory is a "special feature" of the AFS backup system, which takes a read-only snapshot of your home directory, at some time in the early morning hours, from which the system backups are made. The contents of this directory DO NOT count against a user's quota.