Intel 7xx Servers User Manual
Chapter 3. Batch Performance
In a commercial environment, batch workloads tend to be I/O intensive rather than CPU intensive. The
factors that affect batch throughput for a given batch application include the following:
factors that affect batch throughput for a given batch application include the following:
y Memory (Pool size)
y CPU (processor speed)
y DASD (number and type)
y System tuning parameters
y CPU (processor speed)
y DASD (number and type)
y System tuning parameters
Batch Workload Description
The Batch Commercial Mix is a synthetic batch workload designed to represent multiple types of batch
processing often associated with commercial data processing. The different variations allow testing of
sequential vs random file access, changing the read to write ratio, generating "hot spots" in the data and
running with expert cache on or off. It can also represent some jobs that run concurrently with interactive
work where the work is submitted to batch because of a requirement for a large amount of disk I/O.
processing often associated with commercial data processing. The different variations allow testing of
sequential vs random file access, changing the read to write ratio, generating "hot spots" in the data and
running with expert cache on or off. It can also represent some jobs that run concurrently with interactive
work where the work is submitted to batch because of a requirement for a large amount of disk I/O.
3.1 Effect of CPU Speed on Batch
The capacity available from the CPU affects the run time of batch applications. More capacity can be
provided by either a CPU with a higher CPW value, or by having other contending applications on the
same system consuming less CPU.
provided by either a CPU with a higher CPW value, or by having other contending applications on the
same system consuming less CPU.
Conclusions/Recommendations
y For CPU-intensive batch applications, run time scales inversely with Relative Performance Rating
(CPWs). This assumes that the number synchronous disk I/Os are only a small factor.
y For I/O-intensive batch applications, run time may not decrease with a faster CPU. This is because
I/O subsystem time would make up the majority of the total run time.
y It is recommended that capacity planning for batch be done with tools that are available for iSeries.
For example,
PATROL for iSeries - Predict from BMC Software, Inc.
* (PID# 5620FIF) can be used
for modeling batch growth and throughput. BATCH400 (an IBM internal tool) can be used for
estimating batch run-time.
estimating batch run-time.
3.2 Effect of DASD Type on Batch
For batch applications that are I/O-intensive, the overall batch performance is very dependent on the
speed of the I/O subsystem. Depending on the application characteristics, batch performance (run time)
will be improved by having DASD that has:
speed of the I/O subsystem. Depending on the application characteristics, batch performance (run time)
will be improved by having DASD that has:
y faster average service times
y read ahead buffers
y write caches
y read ahead buffers
y write caches
Additional information on DASD devices in a batch environment can be found in Chapter 14, “DASD
Performance”.
Performance”.
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
©
Copyright IBM Corp. 2008
Chapter 3 - Batch Performance
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