Oracle Database 11 g - Online Public Access Catalog

CHAPTER 1 ■ INSTALLING, UPGRADING, AND MANAGING CHANGE 43The connection_id parameter signifies a connection from the workload capture (generatedduring replay data initialization), and the replay_connection parameter (an optional parameter)specifies the new connection string to be used during the workload replay. If you leave thereplay_connection parameter’s value set to null (the default value), all replay sessions willconnect to the default host, which is determined by the replay client’s runtime environment.■Note Although Database Replay is a new Oracle Database 11g feature, Oracle will be porting the changecapture portion of this feature back to the Oracle Database 10g Release 2. You can replay any workload youcapture on an Oracle Database 10.2.0.4 release or newer on an Oracle Database 11g based database. So ifyou are running the 10.2 version, you can use the Database Replay feature to check out the impact of an upgradeto the 11.x release of the database once the relevant code is ported to Oracle Database 10g Release 2.Starting the Replay ClientsBefore you can replay the workload, you must ensure that the replay clients connect to the testdatabase. Each thread of the replay client (started by the executable wrc) submits a workloadfrom a session. Once you process the workload data, you must start the replay client(s). Thereplay client connects to the database and drives the replay of the workload data. Before youcan start the replay clients, make sure the replay directory contains the (preprocessed) workloadfiles, the replay clients have access to that directory, and the replay user has the correctcredentials to connect.The wrc executable is run by default in replay mode. However, first run the wrc executablein calibrate mode to estimate the number of replay clients and hosts to replay your capturedworkload. Each replay client can handle multiple user sessions. If, for example, the capturedworkload was generated by 200 user sessions and a single host can handle only about 120 sessions,you’ll need two hosts, with a replay client running on each of those hosts. This means you mustinstall wrc on both the hosts. Here’s how you run the wrc executable in calibrate mode:$ wrc system/ mode=calibrate replay_dir=./test_dirOnce you figure out the number of hosts and replay clients you need to replay the actualworkload, you then start the necessary replay clients by executing the wrc executable in the(default) replay mode, as shown here:$ wrc system/ mode=replay replay_dir=./test_dirBy default, the connection_override parameter of the wrc executable is set to the valueof false, meaning that all replay threads will simply use the connection mappings in theDBA_WORKLOAD_CONNECTION_MAP view to connect.Preparing the Workload ReplayBefore you start the actual workload replay, you must specify various workload replay options.The following are the three replay options you can configure to control the database replay: