Preparation

Either specify N in the pd_redo_allpage_put operand or omit this operand.

Action to take when a mismatch occurs between the original and the mirror duplicate

Before restarting HiRDB, use the LVM function to eliminate the mismatch between the original and the mirror duplicate. Then restart HiRDB.

Preparation

Specify Y in the pd_redo_allpage_put operand. When Y is specified, the full recovery processing performed by HiRDB during a restart writes into the database all pages that were updated at or subsequent to a synchronization point. This processing eliminates the mismatch between the original and the mirror duplicate.

Action to take when a mismatch occurs between the original and the mirror duplicate

There is no need to use the LVM function to eliminate the mismatch between the original and the mirror duplicate. Restart HiRDB immediately. The full recovery processing performed by HiRDB during the restart will make the original and duplicate volumes match.

Note

• Use of this method increases the volume of data written into the database during full recovery processing. Consequently, it will take longer to restart HiRDB than when method 1 is used. To reduce the volume of data that must be written into the database, we recommend that you shorten the synchronization point acquisition interval. Use the pd_log_sdinterval operand to specify the synchronization point acquisition interval.
• In this method, the data that was being written into the database when, due to an error, the OS or server went down or a system switchover occurred is re-written through full recovery processing. In response, LVM writes the data to both the main and secondary volumes, thereby matching the two volumes. This method can therefore eliminate only the mismatch that occurs between the original and the mirror duplicate at the instant when HiRDB goes down. Other types of mismatch that occurs between the original and the mirror duplicate, such as those caused by an error during operation, cannot be eliminated with this method. In such a case, use the LVM function to eliminate the mismatch.

The figure below shows an example of a system configuration when the rapid system switchover facility is used in an environment in which the LVM mirroring facility is used to mirror the database.

In this example, the full recovery processing performed by HiRDB during a restart is used to eliminate a mismatch between the original and the mirror duplicate.

Figure 20-11 Example of a system configuration in which the rapid system switchover facility is used

Explanation

• In a system configuration in which the rapid system switchover facility is used, position the Hitachi disk array system such that it can be accessed from both the primary and secondary systems.
• Specify Y in the pd_redo_allpage_put operand.