Real Application Testing - Expert Oracle RAC Performance Diagnostics and Tuning - page 112

In a RAC environment, both these options allow testing the impact when moving from a single instance to a
RAC configuration. It helps to determine the impact of moving from one instance to two or three instances and
understanding the scalability and capacity requirements to execute the current production workload on the new
configuration.

Database Replay
Like the feature's name, database replay helps to replay the current production workload in another environment.
Such activity will help understand the application behavior on a new hardware or production environment.
Database replay (Figure 5-1 ) involves three major steps:

1. Capture, where the current workload is captured and collected for a user predefined time

interval

2. Prepare, where the workload that is captured in the previous step is prepared for the next

run

3. Run, where the workload captured from an existing production environment is executed

on the new environment

Capture Preprocess Replay

Node 1 Node 1 Node 2 Node 3 Node 4 Node 5

EGCDEV SSKY1 SSKY2 SSKY3 SSKY6 SSKY7

Production Test / Preproduction

Figure 5-1. Database replay steps

Workshop
The workshop is to test workload in from a single instance environment on a 6-node RAC environment.

Workload Capture
In this phase, all external client requests directed to the Oracle database are tracked and stored in binary files called
“capture files” on the system. These files contain all the relevant information, such as SQL statement, bind values, wall
clock time, SCN numbers, and so forth, about the calls that are needed to replay the operation on the preproduction
environment.

Step 1
Ensure that the new environment where the production workload will be executed is all ready for testing. Ensure that
all RAP tests 1, 2, and 3 are completed and the required configuration changes or fixes have been made.
Before beginning the capture process, take a copy/snapshot of the current production database and restore it
on a new test or preproduction environment. This is important because the database needs to be at a state before the
capture begins so the replay on the new environment can have the same state of the rows before the collection begins.