Oracle NZ - Francisco Munoz Alvarez

DB_ULTRA_SAFE is a new parameter introduced with Oracle 11gR1, and a fantastic new GEM for High Availability, that using Data Guard to configure on both the primary and standby will trigger the most comprehensive data corruption prevention and detection (and repair on 11gR2, see **) tool in the market.

** Starting in Oracle Database 11g Release 2 (11.2), the primary database automatically attempts to repair the corrupted block in real time by fetching a good version of the same block from a physical standby database.

Speaking simple, what this new functionality will do is use your Standby Database as a backup to correct automatically any data corruption on your primary database and vice-versa (again on 11.2).

The DB_ULTRA_SAFE initialization parameter also controls other data protection behavior in Oracle Database, such as requiring ASM to perform sequential mirror write I/Os.

You basically need to understand that when setting DB_ULTRA_SAFE it will control the behaviour of DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, or DB_LOST_WRITE_PROTECT parameters for you, which mean:

Lets’ Check  all the parameters affected by DB_ULTRA_SAFE:

• DB_BLOCK_CHECKING (Introduced with Oracle 8.1.6) prevents memory and data corruptions, but it incurs some performance overhead on every block change.
• DB_BLOCK_CHECKSUM (Introduced with Oracle 8.1.6) detects redo and data block corruptions and detect corruptions on the primary database and protect the standby database. This parameter requires minimal CPU resources.
• DB_LOST_WRITE_PROTECT (also introduced with 11gR1) enable or disable a physical standby database to detect lost write corruptions on both the primary and physical standby database.

Important: if you explicitly set the DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, or DB_LOST_WRITE_PROTECT parameters in the initialization parameter file, then the DB_ULTRA_SAFE parameter has no effect and no changes are made to the parameter values. Thus, if you specify the DB_ULTRA_SAFE parameter, do not explicitly set these underlying parameters.

To activate it, all you need to do is follow the following steps:

On the Primary Database:  

1. Set the DB_ULTRA_SAFE=DATA_AND_INDEX initialization parameter using:
2. SQL> alter system set db_ultra_safe=dta_and_index scope=spfile;
3. SQL> shutdown immediate (Shutdown your Database)
4. SQL> startup (This will start your primary Database using your new parameter set in the SPFILE previously)

On the Physical Standby Database: 

1. Set the DB_ULTRA_SAFE=DATA_AND_INDEX initialization parameter using:
2. SQL> alter system set db_ultra_safe=dta_and_index scope=spfile;
3. SQL> startup nomount
4. SQL> alter database mount standby database;
5. SQL> alter database recover managed standby database disconnect from session;

If you are using your Standby Database on Read Only mode you also need to run the follow commands on your Physical Standby DB: 

1. SQL> alter database recover managed standby database cancel;
2. SQL> alter database open read only;

If you decide to change later the Read Only Standby to Standby again, you just will need to run the following command: 

1. SQL> alter database recover managed standby database disconnect from session;

Hoping this information could help you in the future,

Francisco Munoz Alvarez

Example done on primary:

Example done at the Standby:

Technorati Tags: DB_ULTRA_SAFE,HIGH AVAILABILITY,BLOCK CORRUPTION,DATA CORRUPTION

I’m writing this post due that I receive this question almost once a week regarding OEM installations.
If you see this error when installing your Oracle Enterprise Manager (Grid Control 10.2.0.3) at OEL 5 or RHEL 5:

/home/oracle/OracleHomes/oms10g/Apache/Apache/bin/httpd: error while loading shared libraries: libdb.so.2: cannot open shared object file: No such file or directory

Don’t panic, all you need to do is:

1. Connect as root
2. Run : ln -s /usr/lib/libgdbm.so.2.0.0 /usr/lib/libdb.so.2
3. Problem solved, for more information please refer to: http://download.oracle.com/docs/cd/B19306_01/relnotes.102/b15659/toc.htm#CJAHFHCJ

Kind Regards,

Francisco Munoz Alvarez

The EM (Enterprise Manager) Desktop Widgets are lightweight internet applications that provide persistent desktop access to key Enterprise Manager monitoring and diagnostic information.

Oracle first released the EM Widgets at August 2009, now at December 2009; Oracle has already 3 different Widgets available, they are

• Target Search Monitoring - Provides access to Enterprise Manager Targets via quick and easy target-searching capabilities. Also allows you to mark targets as “favourites” and monitor their status in real time.

• High-Load Databases - Provides a summary of the top 5 databases ordered by the Average Active Sessions performance or load metric. Also provides access to recent ADDM findings (license required) and drill-down to performance pages of monitored databases.

• Service Level & Monitoring - Provides a snapshot of the health of the services, and presents a consolidated view of the most important service data such as availability and current alerts along with the service level. (Require apply the) Enterprise Manager patch# 8869802 before running this widget. 

If you are a DBA and want to try them, please refer to this link to download them: http://www.oracle.com/technology/products/oem/widgets/index.html

Kind Regards,

Francisco Munoz Alvarez