Administering Platform LSF - SAS

Specifying a Mandatory First Execution Host
Chapter 34
Running Parallel Jobs
In general, the first execution host satisfies certain resource requirements that
might not be present on other available hosts.
LSF normally selects the first execution host dynamically according to the
resource availability and host load for a parallel job. You can also specify a
mandatory first execution host.
Specify a mandatory first execution host
Job level
Queue level
Rules
Use an exclamation point (!) to indicate mandatory first execution host. You
can specify first execution host at job submission, or in the queue definition.
Use the -m option of bsub:
% bsub -n 32 -m "hostA! hostB hostC" myjob
hostA is the mandatory first execution host.
Specify the first execution host in the list of hosts in the HOSTS parameter in
lsb.queues:
HOSTS = hostA! hostB hostC
The queue-level specification of mandatory first execution host applies to all
jobs submitted to the queue.
The following rules apply when specifying first execution host:
◆ First execution host cannot be a host group or host partition, even if only
one host is in the group or partition. Jobs that specify a host group or host
partition as first execution host are rejected.
◆ The first execution host must satisfy the corresponding resource
requirement specified at submission or on the queue. The order string in
the resource requirement is ignored: the select, span and rusage strings in
a resource requirement apply to the first execution host but the order string
does not.
If the specified first execution host does not satisfy the resource
requirement, the job will stay in the pending state until the resource
requirement is satisfied.
◆ The first execution host can appear anywhere in the host string, but you
can specify only one first execution host.
If multiple first execution hosts are specified in HOSTS on a queue, only
the first valid first execution host is used, the others will be ignored as if
they were not specified.
◆ The keyword all is ignored if it is specified in the execution host list. The
keyword others is valid in the host list, but it cannot be the first execution
host. Both keywords are ignored if they are specified as the first execution
host.
If the first execution host is incorrect at job submission, the job will be rejected.
If incorrect configurations exist on the queue level, warning messages will be
logged and displayed when LSF starts, restarts or is reconfigured.
Administering Platform LSF 439