The following steps must be performed in order to change the protection modes of Data Guard's configuration using Enterprise Manager Cloud Control:
LOG_ARCHIVE_DEST_n
to convert the SYNC
redo transport mode to ASYNC
. Click on Protection Mode on the Data Guard Administration page, select Maximum Performance, and click on Continue.SYNC
will be changed to ASYNC
. Click on Yes to continue as shown in the following screenshot:LOG_ARCHIVE_DEST_n
parameter showing the standby database that is changed to support the ASYNC
redo transport.ALTER SYSTEM
statement change the LOG_ARCHIVE_DEST_n
parameter to the SYNC
attribute. Then shutdown immediate
and startup mount
will be executed. After the instance starts, we can see that the following changes are applied automatically:ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE PROTECTION; ALTER SYSTEM SET log_archive_trace=0 SCOPE=BOTH SID='TURKEY'; ALTER SYSTEM SET log_archive_format='%t_%s_%r.arc' SCOPE=SPFILE SID='TURKEY'; ALTER SYSTEM SET standby_file_management='MANUAL' SCOPE=BOTH SID='*'; ALTER SYSTEM SET archive_lag_target=0 SCOPE=BOTH SID='*'; ALTER SYSTEM SET log_archive_max_processes=4 SCOPE=BOTH SID='*'; ALTER SYSTEM SET log_archive_min_succeed_dest=1 SCOPE=BOTH SID='*';
These are the Cloud Control managed automatic changes. We should check the values and change the parameters again if necessary. For example, the LOG_ARCHIVE_MAX_PROCESSES
value of 4
may not be sufficient for our Data Guard environment if there is an excessive redo generation rate. So we should set it to a higher value.
However, we see some errors and the status of the database is shown in the screenshot. If we examine the alert log, we can see that the primary database is mounted but not opened. Open the database manually with the ALTER DATABASE OPEN
statement to complete the action.
Congratulations, all the Data Guard management interfaces are used to switch between protection modes and you're ready to perform all kind of mode-change operations. The SQL*Plus interface is the most administrator-controlled interface, but it also has the most number of manual options. Administration is simpler but less controlled with DGMGRL and Cloud Control.
Q1. The discouraging part of using the Maximum Protection mode is its effect on the primary database's performance and availability. Performance is affected by the latencies of the log transport and the apply services, which can be fixed by increasing the network, server, and disk performances. The primary database availability issue is caused by the inaccessibility of the standby database. What can we do to minimize the risk of the standby database's inaccessibility?