Platform LSF Administration Guide Version 6.2

Same String
Administering Platform LSF
274
Same String
You must have the parallel batch job scheduler plugin installed in order to use the
same string.
Parallel jobs run on multiple hosts. If your cluster has heterogeneous hosts, some
processes from a parallel job may for example, run on Solaris and some on SGI IRIX.
However, for performance reasons you may want all processes of a job to run on the
same type of host instead of having some processes run on one type of host and others
on another type of host.
The
same string specifies that all processes of a parallel job must run on hosts with the
same resource.
You can specify the
same string:
◆ At the job level in the resource requirement string of:
❖ bsub
❖ bmod
◆ At the queue-level in lsb.queues in the RES_REQ parameter.
When both queue-level and job-level
same sections are defined, LSF combines both
requirements to allocate processors.
Syntax resource_name [ :resource_name ]...
You can specify any static resource.
When you specify for example,
resource1:resource2, if hosts always have both
resources, the string is interpreted as:
◆ Allocate processors only on hosts that have the same value for resource1 and the
same value for
resource2
If hosts do not always have both resources, it is interpreted as:
◆ Allocate processors either on hosts that have the same value for resource1, or on
hosts that have the same value for
resource2, or on hosts that have the same value
for both
resource1 and resource2
Examples
% bsub -n 4 -R"select[type==SGI6 || type==SOL7] same[type]"
myjob
Run all parallel processes on the same host type. Allocate 4 processors on the same host
type—either SGI IRIX, or Solaris 7, but not both.
% bsub -n 6 -R"select[type==any] same[type:model]" myjob
Run all parallel processes on the same host type and model. Allocate 6 processors on any
host type or model as long as all the processors are on the same host type and model.