RECON(1)                           LAM TOOLS                          RECON(1)


       recon - Check if LAM can be started.


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


       -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

       -d      Turn on debugging.

       -h      Print the command help menu.

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

       -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


       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 pro-
              gram 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 stan-
              dard 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 speci-
       fied  in  the LAMBHOST environment variable.  Otherwise a default file,
       bhost.def, is used.  LAM seaches for <bhost> first in the local  direc-
       tory 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 com-
       munication 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 mod-
       ules.  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

       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 <value>s 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 correspond-
       ing 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 correct-
       ness.  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.


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


       recon -v mynodes
           Check  if  LAM can be started on all the UNIX machines described in
           the boot schema mynodes.  Report about important steps as they  are

       recon -v -a
           Check  if  LAM can be started on all the UNIX machines described in
           the default boot schema.  Report about important steps as they  are
           done.   Check  all  the machines; do not stop after the first error


       rsh(1), tkill(1), bhost(5),  lamboot(1),  lamwipe(1),  lam-helpfile(5),
       lamssi(7), lamssi_boot(7)

LAM 7.1.1                       September, 2004                       RECON(1)

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