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)