Configuration of Snapshot Standby Database in Oracle 11g

Snapshot Standby is a new features introduced in Oracle 11g. A snapshot standby database is a type of updatable standby database that provides full data protection for a primary database. A snapshot standby database receives and archives, but does not apply, redo data from its primary database. Redo data received from the primary database is applied when a snapshot standby database is converted back into a physical standby database, after discarding all local updates to the snapshot standby database.

The main benefits of snapshot standby database is that we can convert the physical standby database into a read-write real time clone of the production database and we can then temporarily use this environment for carrying out any kind of  development testing, QA type work or to test the impact of a proposed production change on an application. 

The best part of this snapshot features is that the Snapshot Standby database in turn uses the Flashback Database technology to create a guaranteed restore point to which the database can be later flashed back to.All the features of the flashback  are inherent in the snapshot standby.

Here we will configure the snapshot standby database

Step 1 : Create the physical standby database 
Create the physical standby database .

Step 2:  Enable Flashack Parameter 

SQL>  alter system set db_recovery_file_dest_size=4G  scope=both  ; 
System altered.

SQL> alter system set db_recovery_file_dest='D:\standby\fra\'  scope=both ; 
System altered.

SQL> show  parameter  db_recovery
NAME                                            TYPE                   VALUE
-----------------------------      -----------      -------------------------
db_recovery_file_dest                string                  D:\standby\fra\
db_recovery_file_dest_size         big integer              4G

Step 3  :  Stop the media recovery process 
SQL> alter database recover managed standby database cancel;
Database altered.

Step 4 : Ensure that the database is mounted, but not open.
SQL> shut immediate
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
SQL> startup mount

Step 5  :  Create guaranteed restore point
SQL> create restore point snapshot_rspt guarantee flashback database;
Restore point created.

Step 6  :  Perform the conversion to snapshot standby database
SQL> alter database convert to snapshot standby ;
Database altered.

SQL> select name,open_mode,database_role from v$database;
NAME           OPEN_MODE            DATABASE_ROLE
---------        --------------        --------------------------
NOIDA           MOUNTED              SNAPSHOT STANDBY

SQL> alter database open;
Database altered.

SQL> select name,db_unique_name ,open_mode,database_role from v$database;
NAME      DB_UNIQUE_NAME    OPEN_MODE          DATABASE_ROLE
-------   ----------------------    ---------------      ------------------------
NOIDA         gurgoan                  READ WRITE        SNAPSHOT STANDBY

Since the database is in read-write mode , so we can make some changes or even change the parameter say tunning parameter and check there performance after converting to physical standby and further flashback the whole changes.

SQL> select name,guarantee_flashback_database  from  v$restore_point;
NAME                                                                                            GUA
-----------------------------------------------------------------      -------
SNAPSHOT_STANDBY_REQUIRED_11/18/2011 20:41:01            YES
SNAPSHOT_RSPT                                                                 YES

While the original physical standby database has been now converted to snapshot database, some changes are happening on the Primary database and those changes are shipped to the standby site but not yet applied. They will accumulate on the standby site and will be applied after the snapshot standby database is converted back to a physical standby database.

Step  7  :  Convert snapshot standby to physical standby 
SQL> shut immediate 
SQL> startup mount

SQL> alter database convert to physical standby ;
Database altered.

SQL>shut immediate
SQL> startup mount

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

SQL> alter database recover managed standby database cancel;
Database altered.

SQL> alter database open;
Database altered.

SQL> select name,open_mode,db_unique_name,database_role from v$database;
NAME      OPEN_MODE        DB_UNIQUE_NAME      DATABASE_ROLE
-------    --------------     -----------------------    ----------------------
NOIDA    READ ONLY          gurgoan                     PHYSICAL STANDBY

SQL> alter database recover managed standby database using current logfile disconnect;
Database altered.

Hence, we finally back to physical standby database.


Enjoy    :-) 

ORA-16606: unable to find property

This error occurs because the apply service state is inconsistent or the named property does not exist . In my case, when i configured the data broker and is working fine. Whenever, i fire the below the command the error occurs as .

DGMGRL> show configuration verbose noida
ORA-16606: unable to find property "noida"

While using the below command it is working fine.

DGMGRL> show configuration verbose

Configuration            - dgnoida
Protection Mode       : MaxPerformance
Databases                 : noida - Primary database
                                : delhi - Physical standby database
Fast-Start Failover   : DISABLED
Configuration Status : SUCCESS


To solve this problem , I crosscheck the archive dest and state of primary database and find that the state of status of log_archive_dest_state_2 is deffered . I enable the dest state and then  disable the configuration and later enable the configuration .Now it's working fine.

DGMGRL> disable configuration
Disabled.
DGMGRL> enable configuration
Enabled.

DGMGRL> show database verbose noida

Database - noida
Role:                        PRIMARY
Intended State          TRANSPORT-ON
Instance(s)               noida
Properties:
    DGConnectIdentifier                      = 'noida'
    ObserverConnectIdentifier             = ''
    LogXptMode                                = 'ASYNC'
    DelayMins                                    = '0'
    Binding                                         = 'optional'
    MaxFailure                                   = '0'
    MaxConnections                          = '1'
    ReopenSecs                                = '300'
    NetTimeout                                 = '30'
    RedoCompression                      = 'DISABLE'
    LogShipping                               = 'ON'
    PreferredApplyInstance              = ''
    ApplyInstanceTimeout                = '0'
    ApplyParallel                              = 'AUTO'
    StandbyFileManagement            = 'AUTO'
    ArchiveLagTarget                      = '0'
    LogArchiveMaxProcesses         = '4'
    LogArchiveMinSucceedDest     = '1'
    DbFileNameConvert                 = ''
    LogFileNameConvert                = ''
    FastStartFailoverTarget             = ''
    StatusReport                             = '(monitor)'
    InconsistentProperties                = '(monitor)'
    InconsistentLogXptProps          = '(monitor)'
    SendQEntries                           = '(monitor)'
    LogXptStatus                           = '(monitor)'
    RecvQEntries                          = '(monitor)'
    HostName                              = 'TECH-199'
    SidName                                = 'noida'
    StaticConnectIdentifier            = '(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=TECH-199)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=noida_DGMGRL)(INSTANCE_NAME=noida)(SERVER=DEDICATED)))'
    StandbyArchiveLocation          = 'D:\archive\'
    AlternateLocation                    = ''
    LogArchiveTrace                    = '0'
    LogArchiveFormat                 = 'ARC%S_%R.%T'
    TopWaitEvents                      = '(monitor)'

Database Status                        :  SUCCESS


Enjoy    :-) 

How to Drop Data Guard Configuration in oracle 11g

Once while configuring the dataguard broker, i faced the ORA-16625 and ORA-16501 . This error occurs beacuse the broker rejects an operation requested by the client when the database required to execute that operation was not reachable from the database where the request was made. If the request modifies the configuration, the request must be processed by the copy of the broker running on an instance of the primary database.

Few days ago i configured the standby database "RED" and broker, later drop it . Next time while configuring the data broker the error occurs as 

DGMGRL> create configuration 'dgnoida'
> as primary database is 'noida'
> connect identifier is 'noida';
Error: ORA-16501: the Data Guard broker operation failed
Error: ORA-16625: cannot reach database "red"
Failed.

To solve this issue, I have remove the data guard broker configuration and then created the dataguard broker. The steps to drop the configuration are as follows :

Step 1 : Stop the standby data guard broker process  
( On Standby )

SQL>show parameter dg_broker
NAME                               TYPE                          VALUE
------------------------   -----------     ----------------------------------------------
dg_broker_config_file1        string             C:\APP\NEERAJS\PRODUCT\11.2.0\
                                                                DBHOME_1\DATABASE\DR1NOIDA.DAT
dg_broker_config_file2       string              C:\APP\NEERAJS\PRODUCT\11.2.0\
                                                                DBHOME_1\DATABASE\DR2NOIDA.DAT
dg_broker_start                  boolean                        True

SQL> alter system set dg_broker_start=false;
System altered.

Step 2 : Diable the archive log state 
(On Primary )
SQL> select dest_id,destination,status from v$archive_dest where target='STANDBY';
DEST_ID      DESTINATION     STATUS
--------       ---------------     ----------
   2                delhi                 VALID

SQL> alter system set log_archive_dest_state_2=defer ;
System altered.

SQL> select dest_id,destination,status from v$archive_dest where target='STANDBY';

DEST_ID      DESTINATION     STATUS
--------       ---------------     ----------
   2                delhi                 DEFERRED


Step 3 : On both system rename or drop the metadata files

SQL> show parameter dg_broker

NAME                               TYPE                          VALUE
------------------------   -----------     ----------------------------------------------
dg_broker_config_file1        string             C:\APP\NEERAJS\PRODUCT\11.2.0\
                                                                DBHOME_1\DATABASE\DR1NOIDA.DAT
dg_broker_config_file2       string              C:\APP\NEERAJS\PRODUCT\11.2.0\
                                                                DBHOME_1\DATABASE\DR2NOIDA.DAT
dg_broker_start                  boolean                        False


Delete or rename the file DR1NOIDA.DAT and DR@NOIDA.DAT .


Enjoy       :-)