Archive for 12/01/2010 - 01/01/2011

Dataguard Notes

I wanted to share my notes on "Oracle Data GuardConcepts and Administration 11g Release 2" document.

11gR1 New Features

· Compression of redo traffic over the network in a Data Guard configuration : This feature improves redo transport performance when resolving redo gaps by compressing redo before it is transmitted over the network.
· You can now find the DB_UNIQUE_NAME of the primary database from the standby database by querying the new PRIMARY_DB_UNIQUE_NAME column in the V$DATABASE view. Also, Oracle Data Guard release 11g ensures each database's DB_UNIQUE_NAME is different. After upgrading to 11g, any databases with the same DB_UNIQUE_NAME will not be able to communicate with each other.
· Heterogeneous Data Guard Configuration: This feature allows a mix of Linux and Windows primary and standby databases in the same Data Guard configuration.

Specific to Redo Apply (Physical Standby Database);
· Real-time query capability of physical standby
· Snapshot standby
· Lost-write detection using a physical standby : A "lost write" is a serious form of data corruption that can adversely impact a database. It occurs when an I/O subsystem acknowledges the completion of a block write in the database, while in fact the write did not occur in the persistent storage. This feature allows a physical standby database to detect lost writes to a primary or physical standby database.
· A number of enhancements in RMAN help to simplify backup and recovery operations across all primary and physical standby databases, when using a catalog. Also, you can use the RMAN DUPLICATE command to create a physical standby database over the network without a need for pre-existing database backups.

11gR2 New Features

· The new ALTER SYSTEM FLUSH REDO SQL statement can be used at failover time to flush unsent redo from a mounted primary database to a standby database, thereby allowing a zero data loss failover to be peformed even if the primary database is not running in a zero data loss data protection mode.
· The FAL_CLIENT database initialization parameter is no longer required.

Specific to Redo Apply (Physical Standby Database);
· A corrupted data block in a primary database can be automatically replaced with an uncorrupted copy of that block from a physical standby database that is operating in real-time query mode. A corrupted block in a physical standby database can also be automatically replaced with an uncorrupted copy of the block from the primary database.

Dataguard on Different Operating Systems

In 10g, dataguard started to support different binaries on primary and standby database servers with the same OS family.  For example Microsoft Windows 64-bit Itanium on primary and Microsoft Windows 32-bit or Microsoft Windows 64-bit for AMD on standby database server. However with 11g, dataguard also supports different OS on primary and standby servers. I wanted to share the support matrix for this feature.

ID
PLATFORM_NAME
Release name
PLATFORM_IDs supported within the same Data Guard configuration when using Data Guard Redo Apply (Physical Standby)
2
Solaris Operating System (SPARC) (64-bit)
6 - Oracle 11g onward, primary database must be non-RAC and non-TDE
3
HP-UX PA-RISC  (64-bit)
4 - Oracle 10g onward, see Support Notes 395982.1 and 414043.1
4
HP-UX Itanium (64-bit)
3 - Oracle 10g onward, see Support Notes 395982.1 and 414043.1
5
HP Tru64 UNIX

6
AIX-Based Systems (64-bit)
2 - Oracle 11g onward, primary database must be non-RAC and non-TDE
7
Microsoft Windows (32-bit)
8, 12  - Oracle 10g onward, see Support Note 414043.1
10 - Oracle 11g onward
11, 13 - Oracle 11g onward, see Support Note 414043.1
8

Microsoft Windows (64-bit Itanium)
7 - Oracle 10g onward, see Support Note 414043.1
12 - Oracle 10g onward
11, 13 - Oracle 11g onward
9
IBM zSeries Based Linux
18 (64-bit zSeries only)
10
Linux (32-bit)
7 - Oracle 11g onward
11, 13 - Oracle 10g onward, see Support Note 414043.1
11
Linux Itanium (64-bit)
10 - Oracle 10g onward, see Support Note 414043.1
13 - Oracle 10g onward
7 - Oracle 11g onward, see Support Note 414043.1
8, 12 - Oracle 11g onward
12
Microsoft Windows 64-bit for AMD
7 - Oracle 10g onward, see Support Note 414043.1
8 - Oracle 10g onward
11, 13 - Oracle 11g onward
13
Linux 64-bit for AMD
7 - Oracle 11g onward, see Support Note 414043.1
10 - Oracle 10g onward, see Support Note 414043.1
11 - Oracle 10g onward
8, 12 - Oracle 11g onward
20 - Oracle 11g onward
15
HP Open VMS

16
Apple Mac OS

17
Solaris Operating System (x86)
20 - Oracle 10g onward, see Support Note 414043.1
18
IBM Power Based Linux
9 (64-bit zSeries only)
19
HP IA OpenVMS

20
Solaris Operating System (AMD64)
13 - Oracle 11g onward
17 - Oracle 10g onward, see Support Note 414043.1

Metalink notes specify some restrictions which you should be aware when using the configuration in question. Some important restrictions are:
  • DG Broker is not supported on different binary configuration with 10g.
  • Logical standby is not supported with 32/64 bit configurations
See 1085687.1 for more details.
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