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  han‐
       dler can be installed with ksignal(2).

       All application processes on all remaining nodes are always informed of the death of a node.  This is al‐
       so  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 de‐
       livered.

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 7.1.4                                          July, 2007                                       LAMSHRINK(1)