Chapter 22. IBM Systems Workload Estimator
22.1 Overview
The IBM Systems Workload Estimator (a.k.a., the Estimator or WLE), located at:
http://www.ibm.com/systems/support/tools/estimator
, is a web-based sizing tool for System i, System p,
and System x. You can use this tool to size a new system, to size an upgrade to an existing system, or to
size a consolidation of several systems. The Workload Estimator allows measurement input to best reflect
your current workload and provides a variety of built-in workloads to reflect your emerging application
requirements. Virtualization can be reflected in the sizing to yield a more robust solution, by using
various types of partitioning and virtual I/O. The Workload Estimator will provide current and growth
recommendations for processor, memory, and disk that satisfy the overall customer performance
requirements.
The Estimator supports sizings dealing with multiple systems, multiple partitions, multiple operating
systems, and multiple time intervals. The Estimator also provides the ability to easily do multiple sizings.
These features can be coordinated by using the functions on the Workload Selection screen.
The Estimator will recommend the system model including processor, memory, and DASD requirements
that are necessary to handle the overall workload with reasonable performance expectations. In the case of
System i5™, the Estimator may also recommend the 5250 OLTP feature or the Accelerator feature. To
use the Estimator, you select one or more workloads and answer a few questions about each workload.
Based on the answers, the Estimator generates a recommendation and shows the predicted CPU utilization
of the recommended system in graphical format. The results can be viewed, printed, or generated in
P
ortable
D
ocument
F
ormat (PDF). The visualize solution function can be used to better understand the
recommendation in terms of time intervals and virtualization. The Estimator can also be optionally linked
to the System Planning Tool so that the configuration and validation may continue.
Sizing recommendations from the Estimator are based on processing capacity, which reflect the system's
overall ability to handle the aggregate transaction rate. Again, this recommendation will yield processor,
memory, and DASD requirements. Other aspects of sizing must also be considered beyond the scope of
this tool. For example, to satisfy overnight batch windows or to deal with single-threaded applications,
there may be additional unique hardware requirements that would allow adequate completion time. Also,
you may need to increase the overall DASD recommendation to ensure that there is enough space to
satisfy the overall storage requirements.
Sizing recommendations start with benchmarks and performance measurements based on well-defined,
consistent workloads. For the built-in workloads in the Estimator, measurements have been done with
numerous systems to characterize the workloads. Most of those workloads have parameters that allow
them to be tailored to best suit the customer environment. This, again, is based on measurements and
feedback from customers and Business Partners. Keep in mind, however, that many of these technologies
are constantly evolving. IBM will continue to refine these workloads and sizing rules of thumb as IBM
and our customers gain more experience.
As with every performance estimate (whether a rule of thumb or a sophisticated model), you always need
to treat it as an estimate. This is particularly true with robust IBM systems that offer so many different
capabilities where each installation will have unique performance characteristics and demands. The
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
©
Copyright IBM Corp. 2008
Chapter 22 - Workload Estimator
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