What is the difference between sync async Lgwr arch and affirm Noaffirm?

What is the difference between sync async Lgwr arch and affirm Noaffirm?

It defines who does redo shipping (ARCH/LGWR) and when redo shipping is acknowledged: when sent to standby site (SYNC) or not (ASYNC), when written to disk at standby site (AFFIRM) or not (NOAFFIRM). LGWR SYNC AFFIRM offers maximum protection because commit is successful only when redo is persisted at standby site.

What is affirm and Noaffirm in Oracle Data Guard?

AFFIRM —specifies that a redo transport destination acknowledges received redo data after writing it to the standby redo log. NOAFFIRM —specifies that a redo transport destination acknowledges received redo data before writing it to the standby redo log.

What is sync and async in dataguard?

The synchronous log transport mode is required for the Maximum Protection and Maximum Availability data protection modes. LogXptMode = (‘ASYNC’): Conversely, asynchronous mode (ASYNC) allows updates (DML) to be committed on the primary server before the log file arrives on the standby servers.

What is log_archive_dest_2?

LOG_ARCHIVE_DEST_n: this parameter is used to transfer the archived redo from the primary database to standby database. Standby to primary in case of switchover. Note: LOG_ARCHIVE_DEST_n destination must have either a LOCATION or SERVICE attribute to specify a local disk directory or a remotely accessed database.

How do I sync data guard?

To configure Far Sync, perform the following steps.

  1. Create a Far Sync control file from a primary and copy it to the Far Sync server.
  2. Mount the Far Sync instance with the Far Sync control file you created.
  3. Set parameters for the primary database.
  4. Set parameters for Far Sync.
  5. Set parameters for the standby database.

What is RFS in dataguard?

RFS [Remote File Server]: As we have seen above RFS process can get redo data either from LNS process or from ARCn process of primary and RFS process can writes redo information to standby redo logs files. Each LNS and ARCn process that communicates with Standby database has its own RFS process.

What is the use of Log_archive_config?

LOG_ARCHIVE_CONFIG enables or disables the sending of redo logs to remote destinations and the receipt of remote redo logs, and specifies the unique database names ( DB_UNIQUE_NAME ) for each database in the Data Guard configuration.

What is log_archive_dest_state_2 defer?

SQL> ALTER SYSTEM SET log_archive_dest_state_2 = DEFER; System altered. DEFER = Specifies that valid destination information and attributes are preserved, but the destination is excluded from archiving operations until re-enabled.

Is Oracle Data Guard synchronous replication?

Data Guard offers two choices of transport services: synchronous and asynchronous. Synchronous redo transport requires a primary database to wait for confirmation from the standby that redo has been received and written to disk (a standby redo log file) before commit success is signaled to the application.

What is Fal_client and FAL_SERVER?

FAL_SERVER used to fetch archive log server for a standby database. Value in FAL_SERVER parameter act as Oracle Net Service name which point to standby database. FAL_CLIENT Parameter. FAL_CLIENT specifies the FAL(fetch archive log) client name that is used by the FAL service.

How do I stop dataguard replication?

You can operate these commands by DGMGRL on any node in the same data guard environment.

  1. DGMGRL Transport Off. To stop transport in DGMGRL, we can set transport off in the primary database.
  2. DGMGRL Apply Off. To stop apply in DGMGRL, we can set apply off in the standby database.
  3. DGMGRL Disable Configuration.

How do I stop Oracle Data Guard?

Data Guard Startup & Shutdown Steps

  1. In this article we will look at Oracle Data Guard startup and shutdown sequence.
  2. Stop log apply service or MRP and shutdown the standby.
  3. Stop log shipping from primary and shutdown primary database.
  4. Startup primary database and enable log shipping.

Can I specify lgwr and Arc n processes for the same destination?

Although you cannot specify both LGWR and ARC n 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.

What happens if arch or lgwr is not specified?

If neither the ARCH or LGWR attribute is specified, the default is ARCH. Redo transport services use ARC n processes when the ARCH attribute is specified, and the log writer process when the LGWR attribute is specified.

How do lgwr and affirm work?

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.

How do the async and affirm attributes affect performance?

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