34 The Business Value of DB2 UDB for z/OS
Regression testing
With DB2 Version 8, IBM significantly increased the amount of testing that is
done. Stress testing time was almost doubled and included multiple concurrent
mixed workloads. Duration of early Quality Partnership Program (QPP) testing
was also doubled. This included using new functions and regression testing.
QPP had cross industry/world-wide customer representation in manufacturing,
banking, securities/investment, retail, distribution, and health care. Real
customer catalogs were converted. Further stress testing was done on a 16-way
zSeries 990 (z990) machine.
IBM understands the investment that businesses have made in DB2. IBM has
raised the bar on testing and is committed to sustaining that investment level.
IBM is serious about shipping new DB2 versions when they are ready.
2.2.4 Controlled enablement of new functionality on version upgrade
In the past, when first putting a new DB2 version in development, it was difficult
to prevent application developers from using the new features during the
transition phase. If such code slipped through and was delivered to production, it
would have failed.
Now in Version 8, there is a formalization of what takes place. The first phase for
Version 8 is the compatibility mode (CM). During this phase, no new function is
possible. However, fallback to Version 7 is possible. When you decide to use new
functionality, you must run an enabling-new-function mode (ENFM) job. When
this job is started, there is no returning to compatibility mode. Then everything is
available, and you switch to new-function mode (NFM).
This migration approach is tighter and gives you more control. IBM does not have
to devote resources to complex fallback coding. This process protects you from
surprises and ensures that new functionality is exercised when you are ready.
2.2.5 Rolling maintenance and new releases without an outage
In a sysplex configuration, DB2 maintenance or a version upgrade to a data
sharing group can be done as a windowless install. You can temporarily redirect
work away from a member while you upgrade it. Members of a data sharing
group can coexist. For example, there can be three members at V8 compatibility
mode and one member still at Version 7. You can do a rolling upgrade without
impacting your workload. This is a considerable advantage and allows your
business be continuously available during the upgrade.

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