BosConfig - Defines server processes for the BOS Server to monitor
file lists the processes that the Basic OverSeer (BOS)
Server monitors on its server machine, and thus defines which AFS server
processes run on the machine. It specifies how the BOS Server reacts when a
process fails, and also defines the times at which the BOS Server
automatically restarts processes as part of performance maintenance. The file
must reside in the /var/lib/openafs/local
directory on each AFS server
A server process entry in the BosConfig
file records the following
- The entry type, which is one of the following:
- Designates a server process that runs periodically instead
of continuously. The BOS Server starts a cron process only at specified
times, not whenever it fails. All standard AFS process entries except
"fs" are simple (there are no standard cron processes).
- Designates a group of interdependent server processes. If
one of the processes fails, the BOS Server must coordinate its restart
with the restart of the other processes in the group, possibly by stopping
There is only one standard entry of this type, for which the conventional
name is "fs". It combines three server processes: the File
Server ( fileserver process), the Volume Server (volserver
process), and the Salvager ( salvager process). These processes all
operate on the same data--the AFS data stored on an AFS server machine's
/vicep partitions and mounted in the AFS filespace--but in
different ways. Grouping the processes prevents them from attempting to
access the same data simultaneously, which can cause corruption.
During normal operation, the Salvager process is not active. If the File
Server process fails, however, the BOS Server stops the Volume Server
process and runs the Salvager process to correct any corruption that
resulted from the failure. (The administrator can also issue the
bos salvage command to invoke the Salvager process.) If the
Volume Server fails, the BOS Server can restart it without stopping the
File Server or running the Salvager.
- Designates a server process that runs independently of any
other on the server machine. If a simple process fails, the BOS Server
does not have to coordinate its restart with any other process.
- The entry name. The conventional name for an entry
in the BosConfig file and the associated process matches the binary
filename. When issuing any bos command that takes the
-instance argument, identify each process by the name used in the
BosConfig file. For a list of the names, see the bos create
- The process's status flag, which determines whether
the BOS Server attempts to start the process in two cases: each time the
BOS Server itself restarts, and when the process fails. The
BosConfig file currently uses a binary notation to indicate whether
the BOS Server attempts to restart the process as necessary or does not
monitor it at all. For the sake of clarity, the AFS documentation refers
to the flags as "Run" and "NotRun" instead. Only a
system administrator, not the BOS Server, can change the flag.
- One or more command parameters which the BOS Server
invokes to start the process or processes associated with the entry:
- A "cron" entry has two command parameters, the
first the complete pathname to the program, and the second the time at
which the BOS Server invokes the program.
- The "fs" entry has three command parameters, each
the complete pathname to the fileserver, volserver, and
salvager programs, in that order.
- A "simple" entry has only one command parameter,
the complete pathname to the program.
In addition to server process entries, the BosConfig
file specifies the
times at which the BOS Server performs two types of automatic process
- The general restart time at which the BOS Server
restarts itself and then each process for which the entry in the
BosConfig file has status flag "Run". The default setting
is Sunday at 4:00 a.m.
- The binary restart time at which the BOS Server
restarts any server process for which the time stamp on the binary file in
the /usr/lib/openafs directory is later than the last restart time
for the process. The default is 5:00 a.m.
Finally, there is an entry specifying whether the BOS Server will start in
Although the BosConfig
file is in ASCII format, it is normally best not
to use a text editor to alter it. The parser is very picky, and incorrectly
formatted entries can prevent server startup in ways that are difficult to
diagnose. Instead, use the appropriate commands from the bos
- The bos create command to create an entry in the
file and start the associated process.
- The bos delete command to remove an entry from the
file after the bos stop command is used to stop the
- The bos getrestart command to display the times at
which the BOS Server performs automatic restarts.
- The bos getrestricted command to display whether the
BOS Server is running in restricted mode.
- The bos setrestart command to set the times at which
the BOS Server performs automatic process restarts.
- The bos setrestricted command to place the BOS
Server in restricted mode.
- The bos start command to change an entry's status
flag to "Run" and start the associated process.
- The bos status command to display all processes
listed in the file.
- The bos stop command to change an entry's status
flag to "NotRun" and stop the associated process.
There are also bos commands that start and stop processes without changing
entries in the BosConfig
file. The BOS Server reads the
file only when it starts, transferring the information into
its memory. Thus a process's status as represented in the BOS Server's memory
can diverge from its status in the BosConfig
file. The following
commands change a process's status in the BOS Server's memory only:
- The bos restart command restarts a specified set of
processes, all processes, or all processes other than the BOS Server.
- The bos shutdown command stops a process.
- The bos startup command starts a process.
When the BOS Server shuts down, it rewrites BosConfig
, discarding any
changes made manually to that file. To change the configuration for the next
BOS Server restart, instead write a new file to BosConfig.new
exists when the BOS Server starts, BosConfig
be replaced by BosConfig.new
before the BOS Server reads its
configuration. Note that the BOS Server will notice a new BosConfig.new
file whenever the general restart
time is reached, if one is
configured, since the BOS Server restarts itself at that time.
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