LAMSHRINK(1) LAM COMMANDS LAMSHRINK(1)
lamshrink - Shrink a LAM multicomputer.
lamshrink [-hv] [-w <delay>] [-u <userid>] <node> <hostname>
-h Print useful information on this command.
-v Be verbose.
<hostname> Remove the LAM node on this host.
<node> Remove the LAM node with this ID.
-w <delay> Notify processes on the doomed node and pause for <delay> seconds before
-u <userid> Use this userid to access the host.
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 and the
associated host name is given on the command line. Once lamshrink completes, the node ID
is invalid across the remaining nodes. If a different userid is required to access the
host, it is specified with the -u option.
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 infor-
mation 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.
If enabled with lamboot(1), LAM will watch for nodes that fail. The procedure for remov-
ing a node that has failed is the same as lamshrink after the warning step. In particu-
lar, the SIGSHRINK signal is delivered.
lamshrink -v newhost n1
Remove LAM on newhost, known within LAM as node 1. Report about important steps as
they are done.
lamshrink newhost n30 -w 10
Inform all processes on LAM node 30, which is running on newhost, that the node will
be dead in 10 seconds. Wait 10 seconds and remove the node. Operate silently.
lamboot(1), tkill(1), ksignal(2), getroute(2)
LAM 6.5.8 November, 2002 LAMSHRINK(1)