AFS (Andrew File System)

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AFS (Andrew File System)

• A Distributed File System
• Zihou Wang

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Contents

• What is AFS
• Benefits of AFS
• How to use AFS
• Summary

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What is AFS

• AFS is a distributed file system that enables
  file sharing across both local area and wide area
  networks.
• AFS is marketed, maintained, and extended by
  Transarc Corporation.
• AFS is originally developed at the Information
  Technology Center at Carnegie-Mellon University

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Benefit of AFS

• Cache Manager
• Whenever a remote file is accessed a chunk of
  that file gets copied to local disk and so
  subsequent accesses (warm reads) are almost as
  fast as to local disk
• Location independence
• AFS does file mapping (file name to location) at
  the server

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Benefit of AFS (continue)

• Scalability
• AFS cells can range from the small to the massive
  
• Improved security
• AFS makes use of Kerberos to authenticate users
• AFS uses access control lists(ACL) to restrict
  access to file directories

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Benefit of AFS (continue)

• Single systems image
• Every client and server in a network of systems
  use the same view of file store
• Improved system management capability
• Administrators are able to make configuration
  changes from any client in the AFS cell and no
  need to take systems off-line.

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How to use AFS
pwd /afs/nwstg/project/spot ls -l total
44 drwxrwxrwx 3 root system 2048 Aug
22 1439 altmanb drwxr-xr-x 2 altmanb staff
2048 Jul 29 1625 bin drwxrwxrwx 5 root
system 2048 Mar 22 1632 cgi-bin drwxrwxrwx
2 root system 2048 Apr 02 1403
friedman drwxrwxrwx 2 root system 2048
May 23 1319 murthyja drwxrwxrwx 3 root
system 2048 Jul 18 1324 porricelli drwxrwxrw
x 2 altmanb staff 2048 Jul 30 1347
release drwxrwxrwx 8 altmanb staff 2048
Jul 29 1601 spotdata drwxrwxrwx 3 altmanb
staff 2048 Mar 25 1700 spottest drwxrwxrwx
4 root system 2048 Apr 30 1443
wangz drwxrwxrwx 5 root system 2048
Mar 25 1357 webdocs
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How to use AFS (continue)
cd altmanb ksh altmanb Permission denied.
fs listacl altmanb fs You don't have the
required access rights on 'altmanb' fs listacl
wangz Access list for wangz is Normal rights
systemadministrators rlidwka wangz rlidwk
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How to use AFS (continue)
fs listacl cgi-bin Access list for cgi-bin
is Normal rights systemadministrators
rlidwka systemanyuser rl altmanb rlidwk
wangz rlidwk friedman rlidwk porricel rlidwk
murthyja rlidwk
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How to use AFS (continue)
fs listquota wangz Volume Name
Quota Used Used Partition project.spot.wan
gz 100000 12878 13 42
fs help setacl fs setacl set access control list
aliases sa Usage fs setacl -dir ltdirectorygt
-acl ltaccess list entriesgt -clear -negative
-id -if -help Where -clear clear
access list -negative apply to negative
rights -id initial directory acl
(DFS only) -if initial file acl
(DFS only)
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Summary
Usually, AFS is used on UNIX workstation, such as
HP, DEC, SUN, and SGI. Now more and more users
like to use AFS and Transarc have made AFS
available to PCs and Macs as well as Cray (IBM
main frame).