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LOG_ARCHIVE_DEST_n PARAMETER'S ATTRIBUTE
LGWR ARCH ¡½ Specifies whether redo transport services use archiver processes (ARCn) or the log writer process (LGWR) to collect transaction redo data and transmit it to standby destinations. If neither the ARCH or LGWR attributes are specified, the default is ARCH. SYNC
ASYNC ¡½ Specifies that network I/O is to be done synchronously (SYNC) or asynchronously (ASYNC) when archival is performed using the log writer process (LGWR). MANDATORY
OPTIONAL Specifies the policy for reusing online redo log files: ¡½ MANDATORY¡Xspecifies that filled online log files must be successfully archived to the destination before they can be reused. ¡½ OPTIONAL¡Xspecifies that successful archival to the destination is not required before the online redo log file can be made available for reuse. AFFIRM
NOAFFIRM ¡½ AFFIRM¡Xspecifies that all disk I/O to archived redo log files and standby redo log files is performed synchronously and completes successfully before the log writer process continues. ¡½ NOAFFIRM¡Xspecifies that all disk I/O to archived redo log files and standby redo log files is performed asynchronously; the log writer process on the primary database does not wait until the disk I/O completes before continuing. REOPEN
MAX_FAILURE ¡½ REOPEN Specifies the minimum number of seconds before redo transport services should try to reopen a failed destination. ¡½ MAX_FAILURE Controls the consecutive number of times redo transport services attempt to reestablish communication and transmit redo data to a failed destination before the primary database gives up on the destination. LOCATION
SERVICE ¡½ Each destination must specify either the LOCATION or the SERVICE attribute to identify either a local disk directory or a remote database destination where redo transport services can transmit redo data. DB_UNIQUE_NAME
¡½ Specifies a unique name for the database at this destination. VALID_FOR Specifies when redo transport services transmit redo data to a destination, based on the following factors: ¡½ Whether the database is currently running in the primary or the standby role ¡½ Whether online redo log files, standby redo log files, or both are currently being archived on the database at this destination
Minimum Requirements for Data Protection Modes |
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| Maximum Protection | Maximum Availability | Maximum Performance | |||||||||||||||||||||||||||||||||||||||||
| Redo archival process | LGWR | LGWR | LGWR or ARCH | ||||||||||||||||||||||||||||||||||||||||
| Network transmission mode |
SYNC | SYNC | SYNC or ASYNC when using LGWR process. SYNC if using ARCH process | ||||||||||||||||||||||||||||||||||||||||
| Disk write option | AFFIRM | AFFIRM | AFFIRM or NOAFFIRM | ||||||||||||||||||||||||||||||||||||||||
| Standby redo log required? | Yes | Yes | No, but it is recommended | ||||||||||||||||||||||||||||||||||||||||
CHANGING THE PROTECTION MODE
PERFORM. THE FOLLOW STEP ON PRIMARY DATABASE
STEP 1:
SQL> SHUTDOWN IMMEDIATE;
SQL> STARTUP MOUNT;
STEP 2:
ALTER DATABASE SET STANDBY
DATABASE TO MAXIMIZE {PROTECTION | AVAILABILITY | PERFORMANCE}
SQL> ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE AVAILABILITY;
STEP 3:
ALTER DATABASE OPEN;
STEP 4:
Configure the LOG_ARCHIVE_DEST_n parameters
STEP 5:
CONFIRM THE CONFIGURATION
SQL> SELECT PROTECTION_MODE, PROTECTION_LEVEL FROM V$DATABASE;