14 LOG_ARCHIVE_DEST_n Parameter Attributes

AFFIRM and NOAFFIRM

Controls whether redo transport services use synchronous or asynchronous I/O to write redo data to disk:

• AFFIRM—specifies 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.

• NOAFFIRM—specifies 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.

Usage Notes

• These attributes are optional. If neither the AFFIRM nor the NOAFFIRM attribute is specified, the default is NOAFFIRM.

• The AFFIRM attribute specifies that all disk I/O to archived redo log files and standby redo log files is performed synchronously and must complete before the log writer process continues. The AFFIRM attribute:

  • Is one of the required attributes to ensure no data loss will occur if the primary database fails.

  • Can be specified with either the LOCATION or SERVICE attributes for archival operations to local or remote destinations.

  • Can potentially affect primary database performance, as follows:

    • When you specify the LGWR and AFFIRM attributes, the log writer process synchronously writes the redo data to disk, control is not returned to the user until the disk I/O completes, and online redo log files on the primary database might not be reusable until archiving is complete.

    • When you specify the ARCH and AFFIRM attributes, ARCn processes synchronously write the redo data to disk, the archival operation might take longer, and online redo log files on the primary database might not be reusable until archiving is complete.

    • When you specify the ASYNC and AFFIRM attributes, performance is not affected.

  
  

  Note: When the primary database is in the maximum protection or maximum availability mode, destinations defined with the LGWR and SYNC attributes are automatically placed in AFFIRM mode.

  
  

• The NOAFFIRM attribute specifies 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.

• The AFFIRM and NOAFFIRM attributes apply only to archived redo log files and standby redo log files on remote standby destinations and have no effect on disk I/O for the primary database's online redo log files.

• These attributes can be specified with either the LOCATION attribute for local destinations or with the SERVICE attribute for remote destinations.

Examples

The following example shows the AFFIRM attribute for a remote destination.

LOG_ARCHIVE_DEST_3='SERVICE=stby1 LGWR SYNC AFFIRM'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

ALTERNATE

Specifies an alternate archiving destination to be used when the original destination fails.

Usage Notes

• The ALTERNATE attribute is optional. If an alternate destination is not specified, then redo transport services do not automatically change to another destination if the original destination fails.

• You can specify only one alternate destination for each LOG_ARCHIVE_DEST_n parameter, but several enabled destinations can share the same alternate destination.

• Ideally, an alternate destination should specify either:

  • A different disk location on the same local standby database system (shown in Example 14-1)

  • A different network route to the same standby database system (shown in Example 14-2)

  • A remote standby database system that closely mirrors that of the enabled destination

• If no enabled destinations reference an alternate destination, the alternate destination is implied to be deferred, because there is no automatic method of enabling the alternate destination. However, you can enable (or defer) alternate destinations at runtime using either ALTER SYSTEM.

• Any destination can be designated as an alternate destination, given the following restrictions:

  • At least one local mandatory destination is enabled.

  • The number of enabled destinations must meet the defined LOG_ARCHIVE_MIN_SUCCEED_DEST parameter value.

  • A destination cannot be its own alternate.

• Increasing the number of enabled destinations decreases the number of available alternate archiving destinations.

• When a destination fails, its alternate destination is enabled on the next archival operation. There is no support for enabling the alternate destination in the middle of the archival operation because that would require rereading already processed blocks, and so forth. This is identical to the REOPEN attribute behavior.

• If the REOPEN attribute is specified with a nonzero value, the ALTERNATE attribute is ignored unless the MAX_FAILURE attribute has a nonzero value. If the MAX_FAILURE and REOPEN attributes have nonzero values and the failure count exceeds the specified failure threshold, the ALTERNATE destination is enabled. Therefore, the ALTERNATE attribute does not conflict with a nonzero REOPEN attribute value.

Examples

In the sample initialization parameter file in Example 14-1, LOG_ARCHIVE_DEST_1 automatically fails over to LOG_ARCHIVE_DEST_2 on the next archival operation if an error occurs or the device becomes full.

LOG_ARCHIVE_DEST_1='LOCATION=/disk1 MANDATORY ALTERNATE=LOG_ARCHIVE_DEST_2'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_2='LOCATION=/disk2 MANDATORY'
LOG_ARCHIVE_DEST_STATE_2=ALTERNATE

LOG_ARCHIVE_DEST_1='LOCATION=/disk1 MANDATORY'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_2='SERVICE=stby1_path1 OPTIONAL ALTERNATE=LOG_ARCHIVE_DEST_3'
LOG_ARCHIVE_DEST_STATE_2=ENABLE
LOG_ARCHIVE_DEST_3='SERVICE=stby1_path2 OPTIONAL'
LOG_ARCHIVE_DEST_STATE_3=ALTERNATE

ARCH and LGWR

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.

Usage Notes

• These attributes are optional. If neither the ARCH or LGWR attribute is specified, the default is ARCH.

• Redo transport services use ARCn processes when the ARCH attribute is specified, and the log writer process when the LGWR attribute is specified.

  By default, archiving is performed by ARCn processes; you must explicitly specify the LGWR attribute for redo transport services to use the LGWR process. Although you cannot specify both LGWR and ARCn processes for the same destination, you can choose to use the log writer process for some destinations, while archiver processes transmit redo data for other destinations.

• If you change a destination's current archival process (for example, from the ARCn process to the LGWR process), archival processing does not change until the next log switch occurs.

Example

The following example shows the LGWR attribute with the LOG_ARCHIVE_DEST_n parameter. See Section 5.3 for more examples.

LOG_ARCHIVE_DEST_3='SERVICE=denver LGWR'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

DB_UNIQUE_NAME

Specifies a unique name for the database at this destination.

Usage Notes

• This attribute is optional if:

  • The LOG_ARCHIVE_CONFIG=DG_CONFIG initialization parameter is not specified.

  • This is a local destination (specified with the LOCATION attribute).

• This attributes is required if the LOG_ARCHIVE_CONFIG=DG_CONFIG initialization parameter is specified and if this is a remote destination (specified with the SERVICE attribute).

• Use the DB_UNIQUE_NAME attribute to clearly identify the relationship between a primary and standby databases. This attribute is particularly helpful if there are multiple standby databases in the Data Guard configuration.

• The name specified by the DB_UNIQUE_NAME must match one of the DB_UNIQUE_NAME values in the DG_CONFIG list. Redo transport services validate that the DB_UNIQUE_NAME attribute of the database at the specified destination matches the DB_UNIQUE_NAME attribute or the connection to that destination is refused.

• The name specified by the DB_UNIQUE_NAME attribute must match the name specified by the DB_UNIQUE_NAME initialization parameter of the database identified by the destination.

Example

In the following example, the DB_UNIQUE_NAME parameter specifies boston (DB_UNIQUE_NAME=boston), which is also specified with the DB_UNIQUE_NAME attribute on the LOG_ARCHIVE_DEST_1 parameter. The DB_UNIQUE_NAME attribute on the LOG_ARCHIVE_DEST_2 parameter specifies the chicago destination. Both boston and chicago are listed in the LOG_ARCHIVE_CONFIG=DG_CONFIG parameter.

DB_UNIQUE_NAME=boston
LOG_ARCHIVE_CONFIG='DG_CONFIG=(chicago,boston,denver)'
LOG_ARCHIVE_DEST_1='LOCATION=/arch1/ 
  VALID_FOR=(ALL_LOGFILES,ALL_ROLES) 
  DB_UNIQUE_NAME=boston'
LOG_ARCHIVE_DEST_2='SERVICE=Sales_DR 
  VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) 
  DB_UNIQUE_NAME=chicago'

DELAY

Specifies a time lag between when redo data is archived on a physical standby site and when the archived redo log file is applied to the physical standby database.

Usage Notes

• The DELAY attribute is optional. By default there is no delay.

• The DELAY attribute indicates the archived redo log files at the standby destination are not available for recovery until the specified time interval has expired. The time interval is expressed in minutes, and it starts when the redo data is successfully transmitted to, and archived at, the standby site.

• The DELAY attribute may be used to protect a physical standby database from corrupted or erroneous primary data. However, there is a tradeoff because during failover it takes more time to apply all of the redo up to the point of corruption.

• The DELAY attribute does not affect the transmittal of redo data to a physical standby destination.

• If you have real-time apply enabled, any delay that you set will be ignored.

• Changes to the DELAY attribute take effect the next time redo data is archived (after a log switch). In-progress archiving is not affected.

• You can override the specified delay interval at the standby site. To immediately apply an archived redo log file to the physical standby database before the time interval expires, use the NODELAY keyword of the RECOVER MANAGED STANDBY DATABASE clause. For example:

  SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE NODELAY;
  

  
  

  See Also: Oracle Database SQL Reference for information about the NODELAY keyword on the ALTER DATABASE RECOVER MANAGED STANDBY DATABASE statement.

  
  

Examples

You can use the DELAY attribute to set up a configuration where multiple standby databases are maintained in varying degrees of synchronization with the primary database. However, this protection incurs some overhead during failover, because it takes Redo Apply more time to apply all the redo up to the corruption point.

For example, assume primary database A has standby databases B and C. Standby database B is set up as the disaster recovery database and therefore has no time lag. Standby database C is set up with a 2-hour delay, which is enough time to allow user errors to be discovered before they are propagated to the standby database.

The following example shows how to specify the DELAY attribute for this configuration:

LOG_ARCHIVE_DEST_1='LOCATION=/oracle/dbs/'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_2='SERVICE=stbyB LGWR SYNC AFFIRM'
LOG_ARCHIVE_DEST_STATE_2=ENABLE
LOG_ARCHIVE_DEST_3='SERVICE=stbyC DELAY=120'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

DEPENDENCY

Specify this attribute for a standby destination that will receive redo data through shared access to an archival location at another destination. A destination defined with this attribute has a dependency on another destination, which is specified by the DEPENDENCY attribute.

Usage Notes

• The DEPENDENCY attribute is optional. If you do not specify the DEPENDENCY attribute, redo transport services transmit redo data directly to the destination.

• The DEPENDENCY attribute can be specified on a physical standby database or a logical standby database.

  
  

  See Also: Section 5.7.5, "Sharing a Log File Destination Among Multiple Standby Databases"

  
  

• The availability of redo data at a dependent destination relies on the success or failure of redo transmission to the destination that is specified by the DEPENDENCY attribute.

• The DEPENDENCY attribute has the following restrictions:

  • Only standby destinations can have a dependency.

  • The destination specified by the DEPENDENCY attribute can use either the LOCATION or SERVICE attribute.

  • The DEPENDENCY attribute cannot be modified at the session level.

• When one or more destinations are dependent on the same destination, all attributes specified for the dependent destinations still apply. It appears as if the archival operation was performed for each destination, when only one archival operation actually occurred.

  For example, consider that two standby databases are dependent upon the same destination. You can specify different DELAY attributes for each destination, which enables you to maintain a staggered time lag between the primary database and each standby database.

  Similarly, a dependent destination can specify an ALTERNATE destination, which itself might or might not be dependent on the same parent destination.

• A zero data-loss failover cannot be performed to a dependent destination.

LOCATION and SERVICE

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.

Usage Notes

• Either the LOCATION or the SERVICE attribute must be specified. There is no default.

• If you are specifying multiple attributes, specify the LOCATION or SERVICE attribute first in the list of attributes.

• You must specify at least one local disk directory with the LOCATION attribute. This ensures the local archived redo log files are accessible should media recovery of the primary database be necessary. You can specify up to nine additional local or remote destinations. Specifying remote destinations with the SERVICE attribute ensures Data Guard can maintain a transactionally consistent remote copy of the primary database for disaster recovery.

• For the LOCATION attribute, you can specify one of the following:

  • LOCATION=local_disk_directory

    This specifies a unique directory path name for a disk directory on the system that hosts the database. This is the local destination for archived redo log files.

  • LOCATION=USE_DB_RECOVERY_FILE_DEST

    To configure a flash recovery area, you specify the directory or Oracle Storage Manager disk group that will serve as the flash recovery area using the DB_RECOVERY_FILE_DEST initialization parameter. If no local destinations are defined and a flash recovery area has been configured, Data Guard implicitly uses the LOG_ARCHIVE_DEST_10 destination for the flash recovery area. See Section 5.2.3 for more information about flash recovery areas.

• When you specify a SERVICE attribute:

  • You identify remote destinations by specifying the SERVICE attribute with a valid Oracle Net service name (SERVICE=net_service_name) that identifies the remote Oracle database instance to which the redo data will be sent.

    The Oracle Net service name that you specify with the SERVICE attribute is translated into a connection descriptor that contains the information necessary for connecting to the remote database.

    
    

    See Also: Oracle Database Net Services Administrator's Guide for details about setting up Oracle Net service names

    
    

  • Transmitting redo data to a remote destination requires a network connection and an Oracle database instance associated with the remote destination to receive the incoming redo data.

• To verify the current settings for LOCATION and SERVICE attributes, query the V$ARCHIVE_DEST fixed view:

  • The TARGET column identifies if the destination is local or remote to the primary database.

  • The DESTINATION column identifies the values that were specified for a destination. For example, the destination parameter value specifies the Oracle Net service name identifying the remote Oracle instance where the archived redo log files are located.

Examples

Example 1 Specifying the LOCATION Attribute

LOG_ARCHIVE_DEST_2='LOCATION=/disk1/oracle/oradata/payroll/arch/'
LOG_ARCHIVE_DEST_STATE_2=ENABLE

Example 2 Specifying the SERVICE Attribute

LOG_ARCHIVE_DEST_3='SERVICE=stby1'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

MANDATORY and OPTIONAL

Specifies the policy for reusing online redo log files:

• MANDATORY—specifies that filled online log files must be successfully archived to the destination before they can be reused.

• OPTIONAL—specifies that successful archival to the destination is not required before the online redo log file can be made available for reuse.

Usage Notes

• If neither the MANDATORY nor the OPTIONAL attribute is specified, the default is OPTIONAL.

  At least one destination must succeed even if all destinations are designated as optional. If a destination is optional, archiving to that destination may fail, yet the online redo log file is available for reuse and may be overwritten eventually. If the archival operation of a mandatory destination fails, online redo log files cannot be overwritten.

• The LOG_ARCHIVE_MIN_SUCCEED_DEST=n parameter (where n is an integer from 1 to 10) specifies the number of destinations that must archive successfully before the log writer process can overwrite the online redo log files.

  All MANDATORY destinations and non-standby OPTIONAL destinations contribute to satisfying the LOG_ARCHIVE_MIN_SUCCEED_DEST=n count. If the value set for the LOG_ARCHIVE_MIN_SUCCEED_DEST parameter (that defines the minimum number of destinations that must receive redo data successfully before the log writer process on the primary database can reuse the online redo log file) is met, the online redo log file is available for reuse. For example, you can set the parameter as follows:

  # Database must archive to at least two locations before 
  # overwriting the online redo log files.
  LOG_ARCHIVE_MIN_SUCCEED_DEST = 2 
  
  

• You must have at least one local destination, which you can declare OPTIONAL or MANDATORY.

  At least one local destination is operationally treated as mandatory, because the minimum value for the LOG_ARCHIVE_MIN_SUCCEED_DEST parameter is 1.

• The failure of any mandatory destination, including a mandatory standby destination, makes the LOG_ARCHIVE_MIN_SUCCEED_DEST parameter irrelevant.

• The LOG_ARCHIVE_MIN_SUCCEED_DEST parameter value cannot be greater than the number of mandatory destinations plus the number of optional local destinations.

• These attributes do not affect the data protection mode for the destination.

• The BINDING column of the V$ARCHIVE_DEST fixed view specifies how failure affects the archival operation

Examples

The following example shows the MANDATORY attribute:

LOG_ARCHIVE_DEST_1='LOCATION=/arch/dest MANDATORY'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_3='SERVICE=denver MANDATORY'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

MAX_CONNECTIONS

Specifies the maximum number of network connections that will be used to perform remote archival to the destination. If the MAX_CONNECTIONS attribute is set to a value greater than 1, redo transport services use multiple network connections to perform remote archivals. Each of these connections use a separate archiver (ARCn) process.

Usage Notes

• The MAX_CONNECTIONS attribute is optional. By default redo transport services use a single network connection to perform a remote archival.

  If the MAX_CONNECTIONS attribute is set to a value greater than 1, redo transport services use multiple network connections to perform a remote archival to the destination.

• The LOG_ARCHIVE_MAX_PROCESSES and PARALLEL_MAX_SERVERS initialization parameters are related to the MAX_CONNECTIONS attribute and affect the actual number of ARCn processes used by an instance.

  For example, if the total of MAX_CONNECTIONS attributes on all destinations exceeds the value of LOG_ARCHIVE_MAX_PROCESSES, then Data Guard will use as many ARCn processes as possible but the number of connections may be less than is specified by MAX_CONNECTIONS.

Examples

The following example shows the MAX_CONNECTIONS attribute:

LOG_ARCHIVE_DEST_1='LOCATION=/arch/dest'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_3='SERVICE=denver MAX_CONNECTIONS=3'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

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.

Usage Notes

• The MAX_FAILURE attribute is optional. By default, there are an unlimited number of archival attempts to the failed destination.

• This attribute is useful for providing failure resolution for destinations to which you want to retry transmitting redo data after a failure, but not retry indefinitely.

• When you specify the MAX_FAILURE attribute, you must also set the REOPEN attribute. Once the specified number of consecutive attempts is exceeded, the destination is treated as if the REOPEN attribute was not specified.

• You can view the failure count in the FAILURE_COUNT column of the V$ARCHIVE_DEST fixed view. The related column REOPEN_SECS identifies the REOPEN attribute value.

  
  

  Note: Once the failure count for the destination reaches the specified MAX_FAILURE attribute value, the only way to reuse the destination is to modify the MAX_FAILURE attribute value or any attribute. This has the effect of resetting the failure count to zero (0).

  
  

• The failure count is reset to zero (0) whenever the destination is modified by an ALTER SYSTEM SET statement. This avoids the problem of setting the MAX_FAILURE attribute to a value less than the current failure count value.

• Once the failure count is greater than or equal to the value set for the MAX_FAILURE attribute, the REOPEN attribute value is implicitly set to zero, which causes redo transport services to transport redo data to an alternate destination (defined with the ALTERNATE attribute) on the next archival operation.

• Redo transport services attempt to archive to the failed destination indefinitely if you do not specify the MAX_FAILURE attribute (or if you specify MAX_FAILURE=0), and you specify a nonzero value for the REOPEN attribute. If the destination has the MANDATORY attribute, the online redo log file is not reusable until it has been archived to this destination.

Examples

The following example allows redo transport services up to three consecutive archival attempts, tried every 5 seconds, to the arc_dest destination. If the archival operation fails after the third attempt, the destination is treated as if the REOPEN attribute was not specified.

LOG_ARCHIVE_DEST_1='LOCATION=/arc_dest REOPEN=5 MAX_FAILURE=3'
LOG_ARCHIVE_DEST_STATE_1=ENABLE

NET_TIMEOUT

Specifies the number of seconds the log writer process on the primary system waits for status from the network server (LNSn) process before terminating the network connection.

Usage Notes

• The NET_TIMEOUT attribute is optional. However, if you do not specify the NET_TIMEOUT attribute it will be set to 180 seconds, but the primary database can potentially stall. To avoid this situation, specify a small, nonzero value for the NET_TIMEOUT attribute so the primary database can continue operation after the user-specified timeout interval expires when waiting for status from the network server.

• The NET_TIMEOUT attribute is used only when the log writer process transmits redo data using a network server (LNSn) process.

• The log writer process waits for the specified amount of time to receive status about the network I/O. If there is a possible network disconnection, even one that was terminated due to a network timeout, the log writer process automatically tries to reconnect to the standby database to resolve network brownouts and false network terminations. Typically, except when the network is physically broken, the log writer process can successfully reconnect to the network. The reconnection attempts continue for a period of time that depends on the following factors:

  • The value of the NET_TIMEOUT attribute on the primary database.

  • The protection mode of the primary database, which determines the maximum amount of time that the reconnection will take. Use the following time estimates as a guideline for how long the log writer process will try to reconnect to the standby database:

    • In maximum protection mode, the log writer process tries to reconnect for approximately 5 minutes.

    • In maximum availability mode, the log writer process tries to reconnect within the NET_TIMEOUT value. for approximately 15 seconds

  For example, a primary database operating in the maximum availability protection mode with a NET_TIMEOUT attribute value set to 60 seconds could actually take a minimum of 1 minute to connect or up to 3 minutes to terminate the connection to the standby database.

  
  

  Caution: Be careful to specify a reasonable value for the NET_TIMEOUT attribute when running in maximum protection mode. A false network failure detection might cause the primary instance to shut down.

  
  

• Without careful coordination of the timeout parameter values on the primary and standby systems, it is possible that the primary system might detect a network problem and disconnect, while the standby database might not recognize the network disconnection if its default network timeout values are too high. If the network timers are not set up properly, subsequent attempts by the log writer process on the primary database to attach to the standby database will fail because the standby database has not yet timed out and the broken network connection still appears to be valid. See Oracle Database Net Services Administrator's Guide.

Examples

The following example shows how to specify a 40-second network timeout value on the primary database with the NET_TIMEOUT attribute.

LOG_ARCHIVE_DEST_2='SERVICE=stby1 LGWR NET_TIMEOUT=40 SYNC'
LOG_ARCHIVE_DEST_STATE_2=ENABLE

NOREGISTER

Indicates that the location of the archived redo log file is to be recorded at the corresponding destination.

Usage Notes

• The NOREGISTER attribute is optional if the standby database destination is a part of a Data Guard configuration.

• The NOREGISTER attribute is required if the destination is not part of a Data Guard configuration.

• This attribute pertains to remote destinations only. The location of each archived redo log file is always recorded in the primary database control file.

Examples

The following example shows the NOREGISTER attribute:

LOG_ARCHIVE_DEST_5='NOREGISTER'

REOPEN

Specifies the minimum number of seconds before redo transport services should try to reopen a failed destination.

Usage Notes]

• The REOPEN attribute is optional.

• Redo transport services attempt to reopen failed destinations at log switch time.

• Redo transport services check if the time of the last error plus the REOPEN interval is less than the current time. If it is, redo transport services attempt to reopen the destination.

• REOPEN applies to all errors, not just connection failures. These errors include, but are not limited to, network failures, disk errors, and quota exceptions.

• If you specify REOPEN for an OPTIONAL destination, it is possible for the Oracle database to overwrite online redo log files if there is an error. If you specify REOPEN for a MANDATORY destination, redo transport services will stall the primary database when it is not possible to successfully transmit redo data. When this situation occurs, consider the following options:

  • Change the destination by deferring the destination, specifying the destination as optional, or changing the SERVICE attribute value.

  • Specify an alternate destination.

  • Disable the destination.

  
  

  See Also: Section 5.5, "What to Do If Errors Occur" for more information about using the REOPEN, MAX_FAILURES, and ALTERNATE attributes to specify what actions are to be taken when archival processing to a destination fails

  
  

Examples

The following example shows the REOPEN attribute.

LOG_ARCHIVE_DEST_3='SERVICE=stby1 MANDATORY REOPEN=60'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

SYNC and ASYNC

Specifies that network I/O is to be done synchronously (SYNC) or asynchronously (ASYNC) when archival is performed using the log writer process (LGWR).

Usage Notes

• The SYNC and ASYNC attributes are optional:

  • When you specify the LGWR attribute but you do not specify either the SYNC or ASYNC attribute, the default is SYNC.

  • When you specify the ARCH attribute, only the SYNC attribute is valid. An error message is returned if you specify the ARCH and ASYNC attributes together.

• The SYNC attribute specifies that network I/O is to be performed synchronously for the destination, which means that once the I/O is initiated, the log writer process waits for the I/O to complete before continuing. The SYNC attribute is one requirement for setting up a no-data-loss environment, because it ensures the redo records are successfully transmitted to the standby destination before continuing.

• The ASYNC attribute specifies that network I/O is to be performed asynchronously for the destination.

Examples

The following example shows the SYNC attribute with the LOG_ARCHIVE_DEST_n parameter.

LOG_ARCHIVE_DEST_3='SERVICE=stby1 LGWR SYNC'
LOG_ARCHIVE_DEST_STATE_3=ENABLE

TEMPLATE

Defines a directory specification and format template for names of archived redo log files at the destination. The template is used to generate a filename that is different from the default filename format defined by the STANDBY_ARCHIVE_DEST and LOG_ARCHIVE_FORMAT initialization parameters at the standby destination.

Usage Notes

• The TEMPLATE attribute is optional. If TEMPLATE is not specified, archived redo logs are named using the value of the STANDBY_ARCHIVE_DEST and LOG_ARCHIVE_FORMAT initialization parameters.

• The TEMPLATE attribute overrides the STANDBY_ARCHIVE_DEST and LOG_ARCHIVE_FORMAT initialization parameter settings at the remote archival destination.

• The TEMPLATE attribute is valid only with remote destinations (that is, destinations specified with the SERVICE attribute).

• If specified for a destination that also specifies the LGWR attribute, rearchiving by the ARCn process does not use the TEMPLATE filename specification.

• The value you specify for filename_template must contain the %s, %t, and %r directives described in Table 14-1.

  Table 14-1 Directives for the TEMPLATE Attribute

  Directive	Description
  %t	Substitute the instance thread number.
  %T	Substitute the instance thread number, zero filled.
  %s	Substitute the log file sequence number.
  %S	Substitute the log file sequence number, zero filled.
  %r	Substitute the resetlogs ID.
  %R	Substitute the resetlogs ID, zero filled.

  
  

• The filename_template value is transmitted to the standby destination, where it is translated and validated before creating the filename.

Examples

In the following example, prmy1 transmits redo data to the remote destination, stby1. The TEMPLATE attribute indicates that stby1 is located in the directory /usr/oracle/prmy1 with the p1_thread#_sequence#_resetlogs.dbf filename format.

LOG_ARCHIVE_DEST_1='SERVICE=boston MANDATORY REOPEN=5
    TEMPLATE=/usr/oracle/prmy1/p1_%t_%s_%r.dbf'
LOG_ARCHIVE_DEST_STATE_1=ENABLE

VALID_FOR

Specifies when redo transport services transmit redo data to a destination, based on the following factors:

• Whether the database is currently running in the primary or the standby role

• Whether online redo log files, standby redo log files, or both are currently being archived on the database at this destination

Usage Notes

• The VALID_FOR attribute is optional. However, Oracle recommends that you define a VALID_FOR attribute for each destination so that your Data Guard configuration operates properly after a role transition.

  
  

  Note: Although the (ALL_LOGFILES,ALL_ROLES) keyword pair is the default, it is not appropriate for every destination. For example, if the destination is a logical standby database, which is an open database that is creating its own redo data, the redo data being transmitted by redo transport services could potentially overwrite the logical standby database's local online redo log files.

  
  

• To configure these factors for each LOG_ARCHIVE_DEST_n destination, you specify this attribute with a pair of keywords: VALID_FOR=(redo_log_type,database_role):

  • The redo_log_type keyword identifies the destination as valid for archiving one of the following:

    • ONLINE_LOGFILE—This destination is valid only when archiving online redo log files.

    • STANDBY_LOGFILE—This destination is valid only when archiving standby redo log files.

    • ALL_LOGFILES— This destination is valid when archiving either online redo log files or standby redo log files.

  • The database_role keyword identifies the role in which this destination is valid for archiving:

    • PRIMARY_ROLE—This destination is valid only when the database is running in the primary role.

    • STANDBY_ROLE—This destination is valid only when the database is running in the standby role.

    • ALL_ROLES—This destination is valid when the database is running in either the primary or the standby role.

• If you do not specify the VALID_FOR attribute for a destination, by default, archiving online redo log files and standby redo log files is enabled at the destination, regardless of whether the database is running in the primary or the standby role. This default behavior is equivalent to setting the (ALL_LOGFILES,ALL_ROLES) keyword pair on the VALID_FOR attribute. For example:

  LOG_ARCHIVE_DEST_1='LOCATION=/disk1/oracle/oradata/payroll/arch/ 
    VALID_FOR=(ALL_LOGFILES,ALL_ROLES)
  
  

• The VALID_FOR attribute enables you to use the same initialization parameter file for both the primary and standby roles.

Example

The following example shows the default VALID_FOR keyword pair:

LOG_ARCHIVE_DEST_1='LOCATION=/disk1/oracle/oradata VALID_FOR=(ALL LOGFILES, ALL_ROLES)'

When this database is running in either the primary or standby role, destination 1 archives all log files to the /disk1/oracle/oradata local directory location.

See the scenarios in Section 12.1 for detailed examples of various Data Guard configurations using the VALID_FOR attribute.

VERIFY

Indicates whether or not an archiver (ARCn) process should scan and verify the correctness of the contents of a completed archived redo log file, either local or remote, after successfully completing the archival operation.

Usage Notes

• If the VERIFY attribute is not specified, archived redo log files will not be verified.

• The verification is significantly more thorough than the normal checksum verification that is always performed; the redo verification may take a substantial amount of time to complete.

• The use of the VERIFY attribute may have an affect on primary database performance.

Example

The following example shows the VERIFY attribute:

LOG_ARCHIVE_DEST_1='LOCATION=/disk1/oracle/oradata VERIFY'
LOG_ARCHIVE_DEST_2='LOCATION=/arch1/SRLs/ VALID_FOR=(STANDBY_LOGFILE, STANDBY_ROLE) VERIFY'
LOG_ARCHIVE_DEST_3='SERVICE=denver VALID_FOR=(ONLINE_LOGFILE,PRIMARY_ROLE) VERIFY'