Platform LSF Administration Guide Version 6.2

Chapter 2
How the System Works
Administering Platform LSF
73
Job Execution Environment
When LSF runs your jobs, it tries to make it as transparent to the user as possible. By
default, the execution environment is maintained to be as close to the submission
environment as possible. LSF will copy the environment from the submission host to
the execution host. The execution environment includes the following:
Environment variables needed by the job
Working directory where the job begins running
Other system-dependent environment settings; for example, resource usage limits
and
umask:
Since a network can be heterogeneous, it is often impossible or undesirable to reproduce
the submission host’s execution environment on the execution host. For example, if
home directory is not shared between submission and execution host, LSF runs the job
in the
/tmp on the execution host. If the DISPLAY environment variable is something
like
Unix:0.0, or :0.0, then it must be processed before using on the execution host.
These are automatically handled by LSF.
To change the default execution environment, use:
A job starter
bsub -L
For resource control, LSF also changes some of the execution environment of jobs.
These include nice values, resource usage limits, or any other environment by
configuring a job starter.
Shared user directories
LSF works best when user home directories are shared across all hosts in the cluster. To
provide transparent remote execution, you should share user home directories on all
LSF hosts.
To provide transparent remote execution, LSF commands determine the user’s current
working directory and use that directory on the remote host.
For example, if the command
cc file.c is executed remotely, cc only finds the
correct
file.c if the remote command runs in the same directory.
LSF automatically creates an
.lsbatch subdirectory in the user’s home directory on
the execution host. This directory is used to store temporary input and output files for
jobs.
Executables and the PATH environment variable
Search paths for executables (the PATH environment variable) are passed to the remote
execution host unchanged. In mixed clusters, LSF works best when the user binary
directories (for example,
/usr/bin, /usr/local/bin) have the same path names on
different host types. This makes the PATH variable valid on all hosts.
LSF configuration files are normally stored in a shared directory. This makes
administration easier. There is little performance penalty for this, because the
configuration files are not frequently read.
See “Default Directory Structures” on page 82 for more information on LSF
installation directories.