Provided by: unfs3_0.9.22+dfsg-2_i386 bug

NAME

       tags - tagged files used for clustering extensions

DESCRIPTION

       Tagged  files are used by ClusterNFS and unfs3 to support NFS exporting
       directories like /etc and /var to a cluster  of  client  machines.  The
       problem  at hand is that different files need to be served to different
       clients. Tagged files provide a way to specify  which  file  should  be
       served to which client(s).

       Tags  are  appended to the end of a filename and are seperated from the
       rest of the name by beginning and ending with $$. For each file,  there
       can  be  multiple  tagged  variants. The normal file, without a tag, is
       only served to clients by default when  no  tagged  file  matching  the
       client is found. The following tags exist:

       file$$$$
              If  a client attempts to access this file, it will be redirected
              to the normal file instead, no matter what  other  tagged  files
              exist.  This  is mainly useful for use inside symlinks that need
              to point to a normal file although other access  to  the  normal
              file should be redirected. In this special case, the tagged file
              file$$$$ does not even need to exist (the symlink will then seem
              to be dangling on the server).

       file$$IP=a.b.c.d$$
              If a client with an IP address of a.b.c.d attempts to access the
              normal file, it will be redirected to this file instead.

       file$$IP=a.b.c.d_n$$
              If a client with an IP adress in the network a.b.c.d/n  attempts
              to  access  the  normal file, it will be redirected to this file
              instead. Note that unfs3 only supports 8, 16, and 24  as  values
              for n.

       file$$HOST=name$$
              If a client with the hostname name attempts to access the normal
              file, it will be redirected to this file instead.

       file$$HOST=name*$$
              If a client whose hostname begins with the string name  attempts
              to  access  the  normal file, it will be redirected to this file
              instead.

       file$$CLIENT$$
              If any client attempts to access the normal  file,  it  will  be
              redirected to this file instead.

       file$$ALWAYS=IP$$
              If  any  client attempts to access or create the normal file, it
              will be redirected to file$$IP=a.b.c.d$$ instead, where  a.b.c.d
              is  the IP address of the client. It does not matter whether the
              target tagged file exists or not.

       file$$ALWAYS=CLIENT$$
              If any client attempts to access or create the normal  file,  it
              will be redirected to file$$CLIENT$$ instead. It does not matter
              whether that file exists or not.

       $$ALWAYS=CLIENT$$
              Like above, but effective for all files in the  directory  where
              it is found.

       $$ALWAYS=IP$$
              Like  above,  but effective for all files in the directory where
              it is found.

       Note that the ALWAYS tag can lead to file not found errors  on  clients
       if  the  tagged files it redirects to does not exist on the server. For
       example, ls(1) can suffer from this problem. Furthermore, this tag is a
       unfs3  extension  and  does  not  exist  in ClusterNFS.  When this tags
       exists, it prevents all access to the normal file by any client.

       file$$CREATE=IP$$
              If  any   client   attempts   to   create   the   normal   file,
              file$$IP=a.b.c.d$$ will be created instead, where a.b.c.d is the
              IP address of the client.

       file$$CREATE=CLIENT$$
              If any client attempts to create the normal file, file$$CLIENT$$
              will be created instead.

       $$CREATE=IP$$
              Like  above,  but effective for all files in the directory where
              it is found.

       $$CREATE=CLIENT$$
              Like above, but effective for all files in the  directory  where
              it is found.

       Tags  work  for  all  kinds  of  named filesystem objects.  If multiple
       tagged files are found for a normal file, they are  considered  in  the
       order  they are given above, starting at the top. Processing stops once
       a match is  found.   In  ClusterNFS,  but  not  in  unfs3,  only  files
       accessible and readable by a client are considered matches.

AUTHOR

       Pascal Schmidt

SEE ALSO

       unfsd(8)

                                  04 Jan 2004                          tags(7)