1. 11g(R1/R2) Data guard Enhancements Suresh Gandhi

2. Agenda What is DATA GUARD ? Types of Data Guard Databases
11g Release 1 Enhancements
11g Release 2 Enhancements
Active Data guard
Snapshot Standby Database
More Features
Rolling Upgrade and Physical Standby
Q&A

3. High Availability & Disaster Recovery Solution
Data Guard Overview
Data Guard
Standby Plus more
High Availability & Disaster Recovery Solution

4. Provides ….

5. Data guard Databases

6. 11G R1 Enhancements
Release 1
New
Features

7. R2 - Enhancements
Release 2
New
Features

8. R2- New Features
Release 2
New
Features

9. Active and Snapshot Standby
Traditional Functionality until 10g
11g Snapshot Standby
11g Active DataGuard

10. Active Data Guard Benefits

11. Turn on Physical Standby to Active Standby
Stop redo apply
Database in standby mount mode
Open readonly
Open mode changed to read only
Start the redo apply again using log file (SRL’s)
Status changed to read only apply

12. Turn on Physical Standby to Snapshot Standby
Once sync check, convert standby to snapshot
Open database
Read write mode
Need to close database
Switched back to physical standby

13. Additional Info – Active / Snapshot
WHAT OPERATION ALLOWED IN ACTIVE DATA GUARD ?
SELECT statements
Complex queries
Calling of stored procedures
Use of database links to redirect DML to Primary
Use of stored procedures to call remote stored procedures via database links
Use of SET ROLE
Use of ALTER SESSION and ALTER SYSTEM
No Datatypes restrictions like Logical Standby
Additional TEMPFILES can be created for Sorts
Flashback Query : SELECT … AS OF <SCN>
Additional License
SOME IMPORTANT POINTS FOR SNAPSHOT STANDBY DATABASE
PHYSICAL STANDBY DATABASE SHOULD BE IN FLASHBACK MODE
NO REAL TIME QUERY OR DATA
NO FAST START FAILOVER IN THIS MODE
NO SWITCHOVER/FAILOVER UNTIL CONVERTED TO PHYSICAL STANDBY
Free of Licence
POINTS
Configure the Flash Recovery Area
Set the Retention Target
Enable Flashback Database

14. 10g Equivalent Snapshot commands
Prepare the physical standby database to be activated
SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE=20G;
SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST='/arch/oradata'
Prepare the primary database to have the physical standby be diverged.
Archive the current log file.
SQL> ALTER SYSTEM ARCHIVE LOG CURRENT;
Cancel Redo Apply and create a guaranteed restore point.
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
SQL> CREATE RESTORE POINT restore_pt GUARANTEE FLASHBACK DATABASE;
Activate the physical standby database.
SQL> ALTER DATABASE ACTIVATE STANDBY DATABASE;
SQL> STARTUP MOUNT FORCE;
SQL> ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE PERFORMANCE;
SQL> ALTER DATABASE OPEN
Revert the ac4vated database back to a physical standby database.
SQL> FLASHBACK DATABASE TO RESTORE POINT restore_pt;
SQL> ALTER DATABASE CONVERT TO PHYSICAL STANDBY;

15. DATGUARD – Still More Features

16. More Features – RMAN Active database Duplication
Steps
Create a pfile with only db_name=stby
Create directory structure for datafile locations
Create directory structure for dump locations
Create a password file (must match with target)
Listener & Tnsnames entries for new standby database
Startup nomount with pfile
Run the rman command in other box
Log File 
RMAN> run {
allocate channel prmy1 type disk;
allocate channel prmy2 type disk;
allocate channel prmy3 type disk;
allocate channel prmy4 type disk;
allocate auxiliary channel repstby type disk;
duplicate target database for standby from active database
spfile
parameter_value_convert 'emrep','repstby'
set db_unique_name='repstby'
set db_file_name_convert='C:\','F:\'
set log_file_name_convert='C:\','F:\' ; }
The FAILGROUP_TYPE column in both the V$ASM_DISK and V$ASM_DISK_STAT views specifies failure group type. The value for this column is REGULAR for regular failure groups and QUORUM for quorum failure groups.

17. More Features – Redo Compression
Requires Advanced Compression features
Compress redo as it is transmitted data
Automatically compress the data as it only resolves gaps
Helpful and useful in bandwidth constrained locations
Syntax:-
LOG_ARCHIVE_DEST_2=‘Service=stby Async compression=ENABLE’

18. More Features – Heterogenous database support
Oracle 10g Dataguard support mixed environments 32bit and 64 bit configuration
Oracle 11G Dataguard supports mixed Windows/Linux in same configuration
Only Physical Standby
Same Endianess required on all platforms
Metalink :

19. More Features: Lost Write Detection
Due to hardware or storage issues lost writes can happen while transmission and blocks may be stale.
Very hard to diagnose in such of case of corruption
Feature:-
Compares version of Blocks
Between Standby blocks and redo stream
Version discrepancy can be either standby or primary
If Primary Database block corruption is detected  Resolved
Using standby failover and
Restore data consistency
New Initialization parameter
ALTER System set db_lost_write_protect = NONE/TYPICAL/FULL
5% impact but increase protection

20. More Features: Automatic Block recovery
11g R2 automatically recovers corrupted blocks from standby copies of blocks
Automatic Block Media Recovery also automatically repair corrupted blocks discovered in the physical standby databases
Reduce recovery time in block corruption cases instead of restoring from tape or disks
RMAN command RECOVER BLOCK can be used for manual recovery and its check for all suitable or consistent blocks across several copies of backups or
Clause can be added RECOVER BLOCK … EXCLUDE STANDBY then wont check in standby
Automatic block recovery is applicable only in physical corruptions like
When checksum is invalid
Block contains all zeros
Block header is fractured

21. More Features: Redo Flush
Yes, Redo can be flushed
Can be done when the primary is in mount mode
To avoid minimal loss of data and allowed failover to be performed without data loss
Syntax:-
ALTER System FLUSH Redo to <target DB Name>

22. More Features: Sync with Primary
New command
ALTER SESSION SYNC WITH PRIMARY
WAIT FOR STANDBY TO BE SYNCHRONIZED WITH PRIMARY
FAILS IF REDO APPLY OR REDO TRANSPORT IS OFF REPORT TRANSPORT AND APPLY LAGS

23. More Features: STANDBY_MAX_DATA_DELAY

24. More Features: ROLE Based services
Services can be created and start based on the database ROLE, viz a new addition sys_context (Database ROLE)
In R2 services can be attached via srvctl
Service can failover when using Cluster or Oracle restart
11gR1 to use triggers based on Database role
Example Trigger

25. Rolling Upgrade : Transient Logical Standby
Physical standby must be converted to Logical Standby and uses Flashback as fall out plan
Downtime for upgrade is only the SWITCHOVER TIME

26. Finally, Monitoring Views
GAP_STATUS , additional column in v$archive_dest – GAP or NO GAP
V$dataguard_stats for transport/apply lag
V$REDO_DEST_RESP_HISTOGRAM
Useful when need to analyse network latencies by checking transport lag
V$STANDBY_EVENT_HISTOGRAM

27. Thank you! Q & A
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