AFS-Glossary

A

• AccessControl
  ACLs are enforced on the directory-level. Within one directory all files have the same protection.
  Available Rights :
  
  • a - administer : change ACL in this directory
  • d - delete : delete a file in a directory
  • i - insert : insert a file in this directoy
  • k - lock : lock files in this directoy
  • l - lookup : change into this directoy
  • r - read : read files
  • w - write : write to files
  Notes :
  • To create new files both i+w rights are necessary.
  • In order to see files in the windows explorer or to do a ls -l on unix, both r+l rights are required.

B

• bosserver :
  server-program which takes care that the other server-programs are running and restarts those in case of a failure
• bos <unix-command> :
  client program to query and manipulate the bosserver.
  

C

• Cell
  a Cell is an adminstrative unit within AFS. All servers and clients belong to one cell. The name of the cell is usually the second directory of the namespace /afs/<cellname>/..., e.g. here it is /afs/ipp-garching.mpg.de/
• CellAlias
  abbreviation of the cellname in the namespace. Here it is e.g. /afs/ipp/ for /afs/ipp-garching.mpg.de/
• Client
  sometimes also referred to as cache-manager.
  Program which provides access to AFS. Listens on port 7001/udp.
• Client-cache
  filespace in memory or disc of the client to store data locally. Thus, data do not have to be retrieved form the server everytime the client accesses them.
  
• Callback
  Mechanism of the fileserver to tell the client, that some files in its cache have been changed by a different client and must be discarded from the client-cache.
  
  

D

E

F

• fs <unix-command> :
  client program to query the fileserver. Gives various information about the files and directory a client is using.
• fileserver :
  server-program which actually serves the file-data. Controlled by the bosserver. Listens on port 7000/udp
• firewall settings client :
  following rules should be applied :
  outgoing connections to afs-servers, ports 7000-7011/udp
  incoming connections from afs-fileservers on port 7000/udp
  

G

H

I

J

K

• Kerberos
  network security framework.
  On Unix there are two free implementations : heimdal and MIT.
  Please note that Kerberos Version 4 should not be used anymore.
  

L

M

• Mountpoint
  point in the namespace to a particular volume.  It is implemented as a symbolic link. A mountpoint may point to a RW or a RO Volume.
  Unix-commands: fs listmount <path>, fs mkmount <path>, fs rmmount <path>

N

O

P

• Protection Server :
  Server-program which deals with users and groups within AFS. Listens on port 7002/udp.
  
• PRDB :
  PRotectionDataBase, used by the Protection server
• pts <unix-command> :
  used to query the protection server in order to create/manipulate groups, users and other things with connected to authorization.
  

Q

R

• RX <network-Protocol> :
  used by AFS for the data connections between client and server, and server and server
• rxdebug <unix-command> :
  client program to query the afs-servers on the network level, prints various information about the peer queried.
  

S

T

• (Kerberos-) Ticket :
  Ticket (as for a ski-lift) identifying you as yourself in a network structure. Used for creating AFS-tokens. Generally known as credential.
• (AFS-) Token :
  Credential which identifies you as a user within AFS. Without a token you will not have write access to AFS. The rights you have within AFS depend on your token and the ACL.

U

• ubik :
  network protocol to synchronize databases on different servers. Used by AFS for the VLDB, PRDB.
  
• udebug <unix-command> :
  client-program to query servers running the ubik protocol.
  

V

• Volume
  Segment of the filespace on a fileserver. Comparable to a partition on a harddisc. Volumes can be moved between servers without almost no interuption of the accessibility.
  Types of Volumes: Readwrite (RW),Readonly(RO),Backup(BK)
• Volumegroup
  group of corresponding RW, RO and BK Volumes. There are only 7 members in a single volumegroup allowed.
• Volserver  (Volume-Server):
  Server-program which deals with volume operations (like release). Controlled by bosserver. Listens on port 7005/udp
• VLServer (VolumeLocation-Server) :
  Server-program which handles the volumelocation database. Controlled by bosserver. Listens on port 7003/udp
• VLDB :
  Volume Location DataBase. Contains information which volume is on what server.
  
• vos <unix-command> :
  client-program to query the volserver and the vlserver.
  

W

X

Y

Z