About external load indices

LSF bases job scheduling and host selection decisions on the resources available within your cluster. A resource is a characteristic of a host (such as available memory) or a cluster that LSF uses to make job scheduling and host selection decisions.

A static resource has a value that does not change, such as a host’s maximum swap space. A dynamic resource has a numeric value that changes over time, such as a host’s currently available swap space. Load indices supply the values of dynamic resources to a host’s load information manager (LIM), which periodically collects those values.

LSF has a number of built-in load indices that measure the values of dynamic, host-based resources (resources that exist on a single host)—for example, CPU, memory, disk space, and I/O. You can also define shared resources (resources that hosts in your cluster share) and make these values available to LSF to use for job scheduling decisions.

If you have specific workload or resource requirements at your site, the LSF administrator can define external resources. You can use both built-in and external resources for LSF job scheduling and host selection.

To supply the LIM with the values of dynamic external resources, either host-based or shared, the LSF administrator writes a site-specific executable called an external load information manager (elim) executable. The LSF administrator programs the elim to define external load indices, populate those indices with the values of dynamic external resources, and return the indices and their values to stdout. An elim can be as simple as a small script, or as complicated as a sophisticated C program.

Note:

LSF does not include a default elim; you should write your own executable to meet the requirements of your site.

The following illustrations show the benefits of using the external load indices feature.

Default behavior (feature not enabled)

With external load indices enabled

Scope

Applicability	Details
Operating system	UNIX Windows A mix of UNIX and Windows hosts
Dependencies	UNIX and Windows user accounts must be valid on all hosts in the cluster and must have the correct permissions to successfully run jobs. All elim executables run under the same user account as the load information manager (LIM)—by default, the LSF administrator (lsfadmin) or root account. External dynamic resources (host-based or shared) must be defined in lsf.shared.