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AFS volumes & quotas

An AFS "volume" contains a subtree of related files and directories descending from a "mount points" that specifies where in the AFS directory tree the volume resides. For example, files for a typical SCS user named bovik would be contained in a dedicated volume called user.bovik and mounted at /afs/cs.cmu.edu/user/bovik.

Types of volumes

SCS supports four main types of AFS volumes:
  • User volumes: Every SCS user has a volume located under /afs/cs.cmu.edu/user/<user_ID>
  • Academic volumes: Instructors teaching graduate courses in SCS can request academic volumes under /afs/cs.cmu.edu/academic
  • Project volumes: Individuals and research projects may request project volumes under /afs/cs.cmu.edu/project/
  • Misc collection volumes are used for Unix software collections

Read-only & read-write volumes

To increase availability in case an AFS server fails, some software (in particular important system software and misc collections) located under /afs/cs.cmu.edu/ is replicated across several file servers. The replicated copies are read-only (they cannot be modified). The corresponding read/write volume is located under /afs/.cs.cmu.edu (note the "." in front of cs.cmu.edu). Every night, the read/write contents are automatically released (copied) to the read-only volumes.

Quotas

Each volume in AFS, including that containing your user files, has an associated quota:
  • The default user-volume quota is 1 GB for new accounts. The maximum user-volume quota is 10 GB.
  • The maximum academic-volume quota is the maximum volume size, 25 GB
  • The maximum project-volume (misc collection) quota is the maximum project-space allocation, 25 GB.

If you require additional space, please contact the SCS Help Desk at <help+@cs.cmu.edu> or x8-4231. If you are using an application that attempts to write to a full volume, the write may fail and data, such as changes to a file you are editing, may be lost. You can use the fs command to see how much free quota remains in a volume.

Determine quota use

The fs command is in /usr/local/bin on Facilitized Unix systems. The following commands will show current quota use for a volume:
fs lq <directory_name>
will list the quota information for the given directory. For example:
 % fs lq /afs/cs/user/bovik
  Volume Name                   Quota      Used %Used   Partition
  user.bovik                    50000     42766   86%         59%
fs lv -dir <directory-name>
will list the current status of the named directory. The available remaining quota is the difference between the maximum quota and the number of blocks used. For example:
 % fs lv /afs/cs/user/bovik
 Volume status for vid = 25836 named user.bovik
 Current disk quota is 50000
 Current blocks used are 42766
 The partition has 7023124 blocks available out of 17212287