DragonFly On-Line Manual Pages

LAMSHRINK(1)                     LAM COMMANDS                     LAMSHRINK(1)

NAME
       lamshrink - Shrink a LAM universe.

SYNOPSIS
       lamshrink [-dhv] [-w delay] nodeid

OPTIONS
       -d            Print detailed debugging information.

       -h            Print useful information on this command.

       -v            Be verbose.

       -w delay      Notify processes on the doomed node and pause for delay
                     seconds before proceeding.

       nodeid        Remove the LAM node with this ID.

DESCRIPTION
       An existing LAM session, initiated by lamboot(1), can be shrunk to
       include less nodes with lamshrink.  One node is removed for each
       invocation.  At a minimum, the node ID is given on the command line.
       Once lamshrink completes, the node ID is invalid across the remaining
       nodes (as can be seen by running lamnodes(1)).

       Existing application processes on the target node can be warned of
       impending shutdown with the -w option.  A LAM signal (SIGFUSE) will be
       sent to these processes and lamshrink will then pause for the given
       number of seconds before proceeding with removing the node.  By
       default, SIGFUSE is ignored.  A different handler can be installed with
       ksignal(2).

       All application processes on all remaining nodes are always informed of
       the death of a node.  This is also done with a signal (SIGSHRINK),
       which by default causes a process's runtime route cache to be flushed
       (to remove any cached information on the dead node).  If this signal is
       re-vectored for the purpose of fault tolerance, the old handler should
       be called at the beginning of the new handler.  The signal does not, by
       itself, give the process information on which node has been removed.
       One technique for getting this information is to query the router for
       information on all relevant nodes using getroute(2).  The dead node
       will cause this routine to return an error.

   FAULT TOLERANCE
       If enabled with lamboot(1), LAM will watch for nodes that fail.  The
       procedure for removing a node that has failed is the same as lamshrink
       after the warning step.  In particular, the SIGSHRINK signal is
       delivered.

EXAMPLES
       lamshrink -v n1 Remove LAM on n1.  Report about important steps as
           they are done.

       lamshrink n30 -w 10
           Inform all processes on LAM node 30, that the node will be dead in
           10 seconds.  Wait 10 seconds and remove the node.  Operate
           silently.

SEE ALSO
       lamboot(1), lamnodes(1), ksignal(2), getroute(2)

LAM 7.1.5b2                       June, 2008                      LAMSHRINK(1)