Ubuntu Manpage: recon - Check if LAM can be started.

Provided by: lam-runtime_7.1.4-6build2_amd64

NAME

       recon - Check if LAM can be started.

SYNOPSIS

       recon [-a] [-b] [-d] [-h] [-v] [-nn] [-np] [-ssi key value] [bhost]

OPTIONS

       -a      Report all host errors.

       -b      Assume  local and remote shell are the same.  This means that only one remote shell invocation is
               used to each node.  If -b is not used, two remote shell invocations are used to each node.

       -d      Turn on debugging.

       -h      Print the command help menu.

       -ssi key value
               Send arguments to various SSI modules.  See the "SSI" section, below.

       -v      Be verbose.

       -nn     Don't add "-n" to the remote agent command line

       -np     Do not force the execution of $HOME/.profile on remote hosts

DESCRIPTION

In order for LAM to be started on a remote UNIX machine, several requirements have to be fulfilled:

1) The machine must be reachable via the network.

2) The user must be able to remotely execute on the machine with the default remote shell program
that was chosen when LAM was configured. This is usually rsh(1), but any remote shell program is
acceptable (such as ssh(1), etc.). Note that remote host permission must be configured such that
the remote shell program will not ask for a password when a command is invoked on remote host.

3) The remote user's shell must have a search path that will locate LAM executables.

4) The remote shell's startup file must not print anything to standard error when invoked non-
interactively.

If any of these requirements is not met for any machine declared in bhost, LAM will not be able to start.
By running recon first, the user will be able to quickly identify and correct problems in the setup that
would inhibit LAM from starting.

The local machine where recon is invoked must be one of the machines specified in bhost.

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 seaches for bhost first in the local directory and then in the
installation directory under etc/.

recon tests each machine defined in bhost by attempting to execute on it the tkill(1) command using its
"pretend" option (no action is taken). This test, if successful, indicates that all the requirements
listed above are met, and thus LAM can be started on the machine. If the attempt is successful, the next
machine is checked. In case the attempt fails, a descriptive error message is displayed and recon stops
unless the -a option is used, in which case recon continues checking the remaining machines.

If recon takes a long time to finish successfully, this will be a good indication to the user that the
LAM system to be started has slow communication links or heavily loaded machines, and it might be
preferable to exclude or replace some of the machines in the system.

SSI (System Services Interface)
The -ssi switch allows the passing of parameters to various SSI modules. LAM's SSI modules are described
in detail in lamssi(7). SSI modules have direct impact on MPI programs because they allow tunable
parameters to be set at run time (such as which boot device driver to use, what parameters to pass to
that driver, etc.).

The -ssi switch takes two arguments: key and value. The key argument generally specifies which SSI
module will receive the value. For example, the key "boot" is used to select which RPI to be used for
starting processes on remote nodes. The value argument is the value that is passed. For example:

recon -ssi boot tm
Tells LAM to use the "tm" boot module for native launching in PBSPro / OpenPBS environments (the tm
boot module does not require a boot schema).

recon -ssi boot rsh -ssi rsh_agent "ssh -x" boot_file
Tells LAM to use the "rsh" boot module, and tells the rsh module to use "ssh -x" as the specific
agent to launch executables on remote nodes.

And so on. LAM's boot SSI modules are described in lamssi_boot(7). This page should be consulted for
specific actions that are taken by, and how to tweak the run-time behavior of each boot module.

The -ssi switch can be used multiple times to specify different key and/or value arguments. If the same
key is specified more than once, the values are concatenated with a comma (",") separating them.

Note that the -ssi switch is simply a shortcut for setting environment variables. The same effect may be
accomplished by setting corresponding environment variables before running lamboot. The form of the
environment variables that LAM sets are: LAM_MPI_SSI_key=value.

Note that the -ssi switch overrides any previously set environment variables. Also note that unknown key
arguments are still set as environment variable -- they are not checked (by lamwipe) for correctness.
Illegal or incorrect value arguments may or may not be reported -- it depends on the specific SSI module.

Remote Executable Invocation
All tweakable aspects of launching executables on remote nodes during recon are discussed in lamssi(7)
and lamssi_boot(7). Topics include (but are not limited to): discovery of remote shell, run-time
overrides of the agent use to launch remote executables (e.g., rsh and ssh), etc.

FILES

       laminstalldir/etc/lam-bhost.def   default boot schema file, where "laminstalldir" is the directory  where
                                         LAM/MPI was installed.

EXAMPLES