LSF Version 7.3 - Administering Platform LSF

Administering Platform LSF 37
How the System Works
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.