Oracle OCP 1Z0 053 Q479(Workload Capture&Replay)

479.Which two statements about workload capture and replay operations are true? (Choose two.)
A. The clients must be created manually on the test machines to perform more realistic testing.
B. Restart the database in RESTRICTED mode before beginning workload replay to enable a clean state
for workload replay.
C. Restart the database in RESTRICTED mode before beginning workload capture to enable a clean
state for capturing the workload.
D. The application state of the capture system must be identical to the application state of the replay
system when the workload replay begins.
Answer: CD

在workload capture時，將資料庫重啟至restrict模式，是因為要確保在啟動workload capture之前，沒有任何其他非SYS使用者會話連線。啟動至restricted，啟動workload capture。
啟動之後，將資料庫再調整至正常模式。

SQL> startup restrict
ORACLE instance started.


Total System Global Area  413372416 bytes
Fixed Size                  2253784 bytes
Variable Size             314575912 bytes
Database Buffers           88080384 bytes
Redo Buffers                8462336 bytes
Database mounted.
Database opened.

SQL> alter system disable restricted session;


System altered.

9.2.1 Restarting the Database

While this step is not required, Oracle recommends that the database be restarted before capturing the workload to ensure that ongoing and dependent transactions are allowed to be completed or rolled back before the capture begins. If the database is not restarted before the capture begins, transactions that are in progress or have yet to be committed will not be fully captured in the workload. Ongoing transactions will thus not be replayed properly, because only the part of the transaction whose calls were captured will be replayed. This may result in undesired replay divergence when the workload is replayed. Any subsequent transactions with dependencies on the incomplete transactions may also generate errors during replay. On a busy system, it is normal to see some replay divergence, but the replay can still be used to perform meaningful analysis of a system change if the diverged calls do not make up a significant portion of the replay in terms of DB time and other such key attributes.

Before restarting the database, determine an appropriate time to shut down the production database before the workload capture when it is the least disruptive. For example, you may want to capture a workload that begins at 8:00 a.m. However, to avoid service interruption during normal business hours, you may not want to restart the database during this time. In this case, you should consider starting the workload capture at an earlier time, so that the database can be restarted at a time that is less disruptive.

Once the database is restarted, it is important to start the workload capture before any user sessions reconnect and start issuing any workload. Otherwise, transactions performed by these user sessions will not be replayed properly in subsequent database replays, because only the part of the transaction whose calls were executed after the workload capture is started will be replayed. To avoid this problem, consider restarting the database in RESTRICTED mode using STARTUP RESTRICT, which will only allow the SYS user to login and start the workload capture. By default, once the workload capture begins, any database instance that are in RESTRICTED mode will automatically switch to UNRESTRICTED mode, and normal operations can continue while the workload is being captured.

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