LAMBOOT(1)

NAME
lamboot - Start a LAM multicomputer.

SYNTAX
lamboot [-dhvxH] [<bhost>]

OPTIONS

-d  Turn on debugging output. This implies -v.

-h  Print the command help menu.

-v  Be verbose.

-x  Run in fault tolerant mode.

-H  Do not display the command header.

DESCRIPTION
The lamboot tool starts the LAM software on each of the machines specified in the boot schema, <bhost>. The user may wish to first run the recon(1) tool to verify that LAM can be started.

Starting LAM is a three step procedure. In the first step, hboot(1) is invoked on each of the specified machines. Then each machine allocates a dynamic port and communicates it back to lamboot which collects them. In the third step, lamboot gives each machine the list of machines/ports in order to form a fully connected topology. If any machine was not able to start, or if a timeout period expires before the first step completes, lamboot invokes wipe(1) to terminate LAM and reports the error.

The remote shell program that is used to invoke commands on remote hosts is set when LAM is configured. It is typically rsh, but can be set to any value by the person who setup/compiled LAM. This program can be overridden at lamboot invocation time by setting the LAMRSH environment variable to a suitable remote shell program. For example:

    setenv LAMRSH "ssh -x"

This will force LAM to use the "ssh" client to invoke programs on remote nodes, and ensure that "ssh" uses the -x command line flag (to suppress the ssh 1.x client series standard information banner that is normally output to the standard error, which would cause lamboot to fail).

The <bhost> file is a LAM boot schema written in the host file syntax. See bhost(5). Instead of the command line, a boot schema can be specified in the LAMBHOST environment variable. Otherwise a default file, bhost.def, is used. LAM searches for <bhost> first in the local directory and then in the installation directory under boot/.

In addition, lamboot uses a process schema for the individual LAM nodes. A process schema (see conf(5)) is a description of the processes which constitute the operating system on a node. In general, the system administrator maintains this file. It is also possible for the user to customize the LAM software with a private process schema.

  Fault Tolerance
If the -x option is given, LAM runs in fault tolerant mode. In this mode, nodes exchange ``heart beat'' messages periodically to make sure all nodes are running and the links connecting them are operational. When a node's heart beats stop, it is declared ``dead'' and all LAM nodes (and processes) are notified. This allows users to write fault tolerant applications that can degrade gracefully, or fully recover by replacing the defunct node with another (see lamgrow(1)). Since this mode introduces a performance penalty, it is not activated by default.

EXAMPLES

lamboot -v
    Start LAM on the machines described in the default boot schema. Report about important steps as they are done.

lamboot mynodes
    Start LAM on the machines described in the boot schema mynodes. Operate silently.

FILES

$LAMHOME/boot/bhost.def default boot schema file

$LAMHOME/boot/conf.lam default process schema file for LAM nodes

SEE ALSO
recon(1), wipe(1), bhost(5), hboot(1), conf(5), lam-helpfile(5)