HP XC System Software User's Guide Version 3.2

The HP XC system has several features that make it optimal for running parallel applications,
particularly (but not exclusively) MPI applications. You can use the bsub command's -n to
request more than one core for a job. This option, coupled with the external SLURM scheduler,
discussed in “LSF-SLURM External Scheduler”, gives you much flexibility in selecting resources
and shaping how the job is executed on those resources.
LSF-HPC reserves the requested number of nodes and executes one instance of the job on the
first reserved node, when you request multiple nodes. Use the srun command or the mpirun
command with the -srun option in your jobs to launch parallel applications. The -srun can be
set implicitly for the mpirun command; see “Submitting a Parallel Job That Uses the HP-MPI
Message Passing Interface” for more information on using the mpirun -srun command.
Most parallel applications rely on rsh or ssh to "launch" remote tasks. The ssh utility is installed
on the HP XC system by default. If you configured the ssh keys to allow unprompted access to
other nodes in the HP XC system, the parallel applications can use ssh. See “Enabling Remote
Execution with OpenSSH” for more information on ssh.
The following table shows exit codes for jobs launched under LSF-HPC integrated with SLURM:
Table 10-1 LSF-HPC with SLURM Job Launch Exit Codes
DescriptionExit Code
Success0
There was a job launch error in SLURM124
There was a job launch error in HPC-LSF125
10.7 LSF-SLURM External Scheduler
The external scheduler option is an important option that can be included when submitting
parallel jobs with LSF-HPC integrated with SLURM. This option
• Provides application-specific external scheduling options for jobs capabilities
• Lets you include several SLURM options in the LSF command line.
For example, you can submit a job to run one task per node when you have a resource-intensive
job that needs to have sole access to the node's full resources. If your job needs particular resources
found only on a specific set of nodes, you can use this option to submit a job to those nodes.
The LSF host options enable you to identify an HP XC system "host" within a larger LSF cluster.
After the HP XC system is selected, LSF-HPC's external SLURM scheduler provides the additional
flexibility to request specific resources within the HP XC system
You can use the LSF-HPC external scheduler functionality within the bsub command and in
LSF-HPC queue configurations. See the LSF bqueues(1) command for more information on
determining how the available queues are configured on HP XC systems.
See “Submitting a Parallel Job Using the SLURM External Scheduler” for information and
examples on submitting jobs with the LSF-SLURM External Scheduler.
10.8 How LSF-HPC and SLURM Launch and Manage a Job
This section describes what happens in the HP XC system when a job is submitted to LSF-HPC.
Figure 10-1 illustrates this process. Use the numbered steps in the text and depicted in the
illustration as an aid to understanding the process.
Consider the HP XC system configuration shown in Figure 10-1, in which
lsfhost.localdomain is the virtual IP name assigned to the LSF execution host, node n16
is the login node, and nodes n[1-10] are compute nodes in the lsf partition. All nodes contain
two cores, providing 20 cores for use by LSF-HPC jobs.
102 Using LSF-HPC