NAME

       CellServDB - Lists the database server machines in AFS cells

DESCRIPTION

       There are two versions of the CellServDB file, both of which have the same format.  One
       version is used by an AFS client and lists all of the database server machines in the
       local cell and any foreign cell that is to be accessible from the local client machine.
       The other version is used on servers and need list only the database servers in the local
       cell; in some configurations it can be a link to the same file the client uses.

   Client CellServDB
       Along with AFSDB and SRV entries in DNS, the client version of the CellServDB file lists
       the database server machines in the local cell and any foreign cell that is to be
       accessible from the local client machine. Database server machines run the Authentication
       Server (optional), Backup Server (optional), Protection Server, and Volume Location (VL)
       Server (the kaserver, buserver, ptserver, and vlserver) processes, which maintain the
       cell's administrative AFS databases.

       The Cache Manager and other processes running on a client machine use the list of a cell's
       database server machines when performing several common functions, including:

       •   Fetching files. The Cache Manager contacts the VL Server to learn the location of the
           volume containing a requested file or directory.

       •   Creating, viewing, and manipulating protection groups. The pts command interpreter
           contacts the Protection Server when users create protection groups or request
           information from the Protection Database.

       •   Populating the contents of the fake root.afs volume mounted at /afs (or the
           alternative mount point specified in cacheinfo) when afsd is run in "-dynroot" mode.
           The default contents of this directory will match the cells listed in the client
           CellServDB file.

       •   Authenticating users. Client-side authentication programs (such as an AFS-modified
           login utility or the klog command interpreter) contact the Authentication Server to
           obtain a server ticket, which the AFS server processes accept as proof that the user
           is authenticated. This only applies to AFS cells using the deprecated Authentication
           Server instead of Kerberos v5 and aklog.

       The Cache Manager reads the CellServDB file into kernel memory as it initializes, and not
       again until the machine next reboots or the client service restarts. To enable users on
       the local machine to continue accessing the cell correctly, update the file whenever a
       database server machine is added to or removed from a cell. To update the kernel-resident
       list of database server machines without rebooting, use the fs newcell command.

       If the client attempts to access an AFS cell not listed in CellServDB and afsd was started
       with the -afsdb option, the Cache Manager will attempt a DNS SRV or AFSDB record lookup
       and dynamically add the database server locations for that cell based on the result of the
       DNS query.  If the -afsdb option was not used, all AFS cells that will be accessed by a
       client machine must either be listed in CellServDB or added with the fs newcell command.

       The CellServDB file is in ASCII format and must reside in the /etc/openafs directory on
       each AFS client machine. Use a text editor to create and maintain it.

       The client version of the CellServDB file is distinct from the server version, which
       resides in the /etc/openafs/server directory on each AFS server machine. The client
       version lists the database server machines in every AFS cell that the cell administrator
       wants the machine's users to be able to access, whereas the server version lists only the
       local cell's database server machines.

   Server CellServDB
       The server version of the CellServDB file lists the local cell's database server machines.
       These machines run the Authentication Server (optional), Backup Server (optional),
       Protection Server, and Volume Location (VL) Server (the kaserver, buserver, ptserver, and
       vlserver) processes, which maintain the cell's administrative AFS databases. The initial
       version of the file is created with the bos setcellname command during the installation of
       the cell's server machine, which is automatically recorded as the cell's first database
       server machine. When adding or removing database server machines, be sure to update this
       file appropriately. It must reside in the /etc/openafs/server directory on each AFS server
       machine. The database server processes, in addition to the usual configuration allowing
       each to be elected synchronization site and coordinate updates, can be set up as readonly
       database clone servers. Such servers can never be elected as the synchronization site.

       The database server processes consult the CellServDB file to learn about their peers, with
       which they must maintain constant connections in order to coordinate replication of
       changes across the multiple copies of each database. The other AFS server processes
       consult the file to learn which machines to contact for information from the databases
       when they need it.

       Although the server CellServDB file is in ASCII format, do not use a text editor to alter
       it. Instead always use the appropriate commands from the bos command suite:

       •   The bos addhost command to add a machine to the file.

       •   The bos listhosts command to display the list of machines from the file.

       •   The bos removehost command to remove a machine from the file.

       In cells that use the Update Server to distribute the contents of the /etc/openafs/server
       directory, it is customary to edit only the copy of the file stored on the system control
       machine. Otherwise, edit the file on each server machine individually. For instructions on
       adding and removing database server machine, see the OpenAFS Quick Start chapter on
       installing additional server machines. Updates to the server CellServDB will trigger
       reloading the cell server configurations automatically in the AFS server processes.

   CellServDB Format
       Both CellServDB files have the same format:

       •   The first line begins at the left margin with the greater-than character (">"),
           followed immediately by the cell's name without an intervening space. Optionally, a
           comment can follow any number of spaces and a octothorpe ("#"), perhaps to identify
           the organization associated with the cell. A variant of this allows the definition of
           a linked cell: after the leading (">") and cell name, a space and a second cell name
           may be listed before the optional spaces, octothorpe and comment.

       •   Each subsequent line in the entry identifies one of the cell's database server
           machines, with the indicated information in order:

           •   The database server machine's IP address in dotted-decimal format, optionally
               enclosed in square braces ("[")("]") to define a non-voting clone.

           •   One or more spaces.

           •   An octothorpe (#), followed by the machine's fully qualified hostname without an
               intervening space. This number sign does not indicate that the hostname is a
               comment. It is a required field.

       No extra blank lines or newline characters are allowed in the file, even after the last
       entry. Their presence can prevent the Cache Manager from reading the file into kernel
       memory, resulting in an error message.

       For the client CellServDB, it may be desirable to make the client aware of a cell (so that
       it's listed by default in /afs when the -dynroot flag to afsd is in use, for instance)
       without specifying the database server machines for that cell.  This can be done by
       including only the cell line (starting with ">") and omitting any following database
       server machine lines. afsd must be configured with the -afsdb option to use DNS SRV or
       AFSDB record lookups to locate database server machines.  If the cell has such records and
       the client is configured to use them, this configuration won't require updates to the
       client CellServDB file when the IP addresses of the database server machines change.

       grand.central.org maintains a list of the database server machines in all cells that have
       registered themselves as receptive to access from foreign cells. When a cell's
       administrators change its database server machines, it is customary to register the change
       with grand.central.org for inclusion in this file. The file conforms to the required
       CellServDB format, and so is a suitable basis for the CellServDB file on a client machine.
       You can download this file from <http://grand.central.org/>.

EXAMPLES

       The following example shows entries for two cells in a client CellServDB file and
       illustrates the required format.

          >example.com         # Example Corporation
          192.12.105.2         #db1.example.com
          192.12.105.3         #db2.example.com
          [192.12.107.3]       #db3.example.com
          >test.example.com example.com   # Example Corporation Test Cell
          192.12.108.57        #testdb1.example.com
          192.12.108.55        #testdb2.example.com

       The following example shows entries for two linked cells in a client CellServDB file. The
       a.example.com cell is linked to the b.example.com cell.

          >b.example.com # B cell
          192.12.108.57 # db1.b.example.com
          >a.example.com b.example.com # A cell
          192.12.105.2 # db1.a.example.com

       In such a setup, if a client is looking for a volume in cell a.example.com and that volume
       doesn't exist, the client will try to find that volume again in cell b.example.com. The
       order is important. You must list the cell being linked before the cell doing the linking.

       The Windows client supports linking in two directions. The UNIX client does not allow
       bidirectional linkage.

SEE ALSO

       afsd(8), bos_addhost(8), bos_listhosts(8), bos_removehost(8), bos_setcellname(8),
       buserver(8), fs_newcell(1), kaserver(8), klog(1), ptserver(8), vlserver(8), upclient(8),
       upserver(8)

       OpenAFS Quick Start

COPYRIGHT

       IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.

       This documentation is covered by the IBM Public License Version 1.0.  It was converted
       from HTML to POD by software written by Chas Williams and Russ Allbery, based on work by
       Alf Wachsmann and Elizabeth Cassell.