ORA-00214: control file version inconsistent with file version

SQL> startup
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size                  2262048 bytes
Variable Size             624954336 bytes
Database Buffers          436207616 bytes
Redo Buffers                5513216 bytes
ORA-00214: control file '+DGDUP/control01.ctl' version 1960 inconsistent with file '+DGDUP/control02.ctl' version 1956

ORA-01624: log %s needed for crash recovery of instance %s (thread %s)

SQL> alter database drop logfile group 3;
alter database drop logfile group 3
*
ERROR at line 1:
ORA-01624: log 3 needed for crash recovery of instance migdb (thread 1)
ORA-00312: online log 3 thread 1: 'D:\APP\INAM\ORADATA\MIGDB\REDO03.LOG'

Migrating non-ASM database to ASM - 11gR2

Requirement: Migrate a database from Non-ASM to ASM.
Environment: Oracle 11gR2 (11.2.0.3) , non-ASM Database: migdb (in Archivelog mode), Diskgroup on ASM: +DGDUP

Change RAC database Name using NID

Scenario: A RAC database "HOMEDB" name is needed to be changed to "HOMEATT"
Environment: 2 node Oracle RAC 11gR2 11.2.0.3 (Windows 2008R2)

Restore RMAN RAC database backup to other RAC enviornment

Scenerio:
We have a disk backup of a 2 nodes RAC database (homedb) and want to restore it to other RAC environment 2 nodes.
Environment:
Source: Oracle RAC 11gR2 11.2.0.3 (Windows 2008R2) , Diskgroups:  +HOMEDBDATA & +HOMEDBFLASH, Instances: homedb1,homedb2

Destination:  Oracle RAC 11gR2 11.2.0.3 (Windows 2008R2) only software installed. No database existing. Diskgroups: +DBDATA & +DBFLASH

FRM-40733 PL/SQL built in DBMS_error_code failed

On client side developer faced the below issue (11gR2 database) and requested for the investigations.

I got the below after research

ORA-02114 - Undocumented error

One of the developer on client side got the error, ORA-02114.

after research I found below.

Snapshot Standby Database - 11gR2

Prerequsite:
Configuring Oracle 11gR2 Data Guard - Physical Standby (without DG Broker) 

Brief:

Snapshot Standby is a new feature introduced in 11g that allows the standby database to be opened in read-write mode for real time testing. When switched back into standby mode, all changes made whilst in read-write mode are lost. This is achieved using flashback database, but the standby database does not need to have flashback database explicitly enabled to take advantage of this feature. Using the Flashback Database technology restore point is guaranteed to which the database can be later flashed back to.

Setting up active dataguard - Oracle 11g

Prerequsite:

Configuring Oracle 11gR2 Data Guard - Physical Standby (without DG Broker)

Once a standby database is configured, it can be opened in read-only mode to allow query access. This is often used to offload reporting to the standby server, thereby freeing up resources on the primary server. When open in read-only mode, archive log shipping continues, but managed recovery is stopped, so the standby database becomes increasingly out of date until managed recovery is resumed.

Converting a Failed Primary Into a Standby Database Using Flashback Database

Brief: After a failover occurs, the original primary database can no longer participate in the Data Guard configuration until it is repaired and established as a standby database in the new configuration. To do this, you can use the Flashback Database feature to recover the failed primary database to a point in time before the failover occurred, and then convert it into a physical or logical standby database in the new configuration.

Configuring Oracle 11gR2 Data Guard - Physical Standby

Brief: Data Guard is an Oracle feature that primarily provides database redundancy. This is done by having a standby (physical copy) database, preferably in another location and on separate disk. This standby database is maintained by applying the changes from the primary database to it. Standby databases can be maintained with either Redo (Physical standby) or SQL (Logical standby).

Restrict development tools on Production

Environment: Oracle 11gR2 Database on Windows 2008R2
Purpose: Implementing business rules to restrict development tools on production. Developers may work on production through these development tools  on-demand.