LSF Version 7.3 - Administering Platform LSF

Administering Platform LSF 503
Running Parallel Jobs
At most, 16 processors can be allocated to this job. If there are less than 16
processors eligible to run the job, this job can still be started as long as the number
of eligible processors is greater than or equal to 4.
Specifying a First Execution Host
In general, the first execution host satisfies certain resource requirements that
might not be present on other available hosts.
By default, LSF selects the first execution host dynamically according to the
resource availability and host load for a parallel job. Alternatively, you can specify
one or more first execution host candidates so that LSF selects one of the candidates
as the first execution host.
Specify a first execution host
To specify one or more hosts or host groups as first execution host candidates, add
the (!) symbol after the host name. You can specify first execution host candidates
at job submission, or in the queue definition.
Job level 1 Use the -m option of bsub:
bsub -n 32 -m "hostA! hostB hostgroup1! hostC" myjob
The scheduler selects either hostA or a host defined in hostgroup1 as the first
execution host, based on the job’s resource requirements and host availability.
2 In a MultiCluster environment, insert the (!) symbol after the cluster name, as
shown in the following example:
bsub -n 2 -m "host2@cluster2! host3@cluster2" my_parallel_job
Queue level The queue-level specification of first execution host candidates applies to all jobs
submitted to the queue.
1 Specify the first execution host candidates in the list of hosts in the HOSTS
parameter in lsb.queues:
HOSTS = hostA! hostB hostgroup1! hostC
Rules Follow these guidelines when you specify first execution host candidates:
◆ If you specify a host group, you must first define the host group in the file
lsb.hosts.
◆ Do not specify a dynamic host group as a first execution host.
◆ Do not specify “all,” "allremote," or “others,” or a host partition as a first
execution host.
◆ Do not specify a preference (+) for a host identified by (!) as a first execution
host candidate.
◆ For each parallel job, specify enough regular hosts to satisfy the CPU
requirement for the job. Once LSF selects a first execution host for the current
job, the other first execution host candidates