NetBatch-Plus Reference Manual

Setting Up the Processing Environment
NetBatch-Plus Reference Manual—522461-002
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2. Plan Schedulers
Information in the table helps you plan schedulers, executors, and classes as well as
defaults sets and jobs. For example, information in the Executor Program, Executor
Program Nodes, and Tape Drives columns helps you plan your system’s schedulers.
The CPU-Bound and I/O-Bound columns contain information helpful in planning
executors and classes. (A CPU-bound job is a job whose processing takes place
predominantly in a CPU, with few references to I/O resources such as disk files and
tapes. Processing of an I/O-bound job, on the other hand, places a heavy demand on
I/O resources but few demands on CPU resources.)
2. Plan Schedulers
Information from your table of existing and potential batch jobs helps you plan the
NetBatch schedulers for your NetBatch-Plus system. You can record this planning
information on another table. The information from this new table lets you derive the
details you need to fully define each scheduler.
Planning Considerations and Recommendations
The number of schedulers you need depends on the number of nodes on your system,
the number of jobs you want to run concurrently, and your organization’s
NetBatch-Plus testing and training needs. This subsection discusses these
dependencies.
As a rule, plan no more than one scheduler on each node where you need batch
processing facilities. A single scheduler on a node is usually enough to satisfy users’
batch processing requirements on that node.
The benefits of limiting the number of schedulers to one per node come from simplified
job and system management. You can manage CPU resources and job flow more
efficiently and easily with one scheduler than with multiple schedulers. Also, you have
only one scheduler database to maintain and one scheduler log file to check for details
of scheduler events. NetBatch-Plus does not prevent you from having more than one
scheduler on a node, but the tradeoff as you increase the number of schedulers is
more complex job and system management.
There are two exceptions to the rule “one scheduler per node.” These exceptions
relate to schedulers needed for testing and training purposes and to the multiple
schedulers necessary when you want to run more than 64 concurrent jobs (the
maximum for a scheduler).
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For testing and training purposes, plan at least one additional scheduler. Staff who
want to test jobs they are developing can use this scheduler for test runs instead of
your production scheduler. Similarly, staff learning how to use NetBatch-Plus can
familiarize themselves with scheduler management functions without the risk of
damaging the production scheduler.
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For processing environments where more than 64 concurrent jobs are likely, you
need as many schedulers as necessary to cope with the job load. For example, if
you want to run 100 jobs concurrently, you need at least two schedulers.