FAQ

ConMan FAQ

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Q:  I'm running ConMan on a large cluster and it crashes every time at startup.
    How do I configure it to handle more than 1024 consoles?

A:  ConMan versions < 0.1.9 are based on select() and are thereby limited by
    the number of file descriptors.  A file descriptor is needed for each
    console, and another is needed for each log file.  If you are logging each
    console, these versions will be unable to open more than ~510 consoles.

    Under Linux, versions >= 0.1.8.3 can sidestep this limitation if they are
    compiled against an increased __FD_SETSIZE in the /usr/include headers.

    Versions >= 0.1.9 are based on poll() and are no longer constrained by
    the number of file descriptors.  The "nofile" (number of open files)
    limit can be increased in the init script by setting "ulimit -n <num>"
    before starting the daemon.

    As of 0.2.8, this limit can be increased in conman.conf via
    "server nofile=N" (substituting N for the maximum number of open files).

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Q:  I have a cluster where each node's serial port is the console for the next
    node.  I would like to be able to access all consoles from a single host.
    Is there a "serial port forwarding" mechanism to forward the local serial
    port to a single conmand daemon?

A:  ConMan does not currently support forwarding consoles from one daemon to
    another.  However, several serial port forwarders exist:

      http://freshmeat.net/projects/sredird/
      http://freshmeat.net/projects/sercd/
      http://freshmeat.net/projects/ser2net/
      http://freshmeat.net/projects/msredird/

    Chris Worley reports success with ser2net:

    > Date:    Tue, 02 May 2006 11:12:09 -0700
    > From:    "Worley, Chris B" <chris.b.worley@intel.com>
    > Subject: RE: Conman via distributed serial ports
    >
    > Ser2net works great.
    >
    > I setup my "/etc/ser2net.conf" file on each node with:
    >
    >   2299:telnet:100000:/dev/modem:57600,NONE,1STOPBIT,8DATABITS,-RTSCTS,-XONXOFF
    >
    > And my /etc/conman.conf as:
    >
    >   CONSOLE name="n1" dev="/dev/ttyUSB0" log="n1"
    >   CONSOLE name="n2" dev="n1:2299" log="n2"
    >   CONSOLE name="n3" dev="n2:2299" log="n3"
    >   CONSOLE name="n4" dev="n3:2299" log="n4"
    >   CONSOLE name="n5" dev="n4:2299" log="n5"
    >   CONSOLE name="n6" dev="n5:2299" log="n6"
    >   CONSOLE name="n7" dev="n6:2299" log="n7"
    >   CONSOLE name="n8" dev="n7:2299" log="n8"
    >
    > And run ser2conf on each node from inittab with:
    >
    >   ser2net -n -p 2298

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