DATA GUARD CONFIGURATION MODES
- MAXIMUM PROTECTION MODE :
- if you want Architect A no data loss solution ,recommended to configure data guard in maximum protection mode.
- In this mode, it is to create stand by redo logs which are of the same size of primary redo logs .In this mode, user gets commit complete acknowledgement once the data has been written to the primary redo logs as well as standby redo logs.
- If primary unable to send the data to at least one stand by , primary goes down automatically, with out giving commit complete acknowledgement .
Note: upto 10g, we can configure maximum of “ 9” physical stand by , where as per 11g, we can configure maximum of upto “ 30” physical standby’s.
- MAXIMUM PERFORMANCE MODE:
- In this mode , it is not necessary to create stand by redo logs.
- User gets commit complete acknowledgement once the data has been written to the primary redo logs.
- With this mode , we cant achive “ a no data loss solution”
- MAXIMUM AVAILABILTY MODE:
- Initially configuration works in protection mode . if primary enable to ship the data to a least one stand by , primary will not goes down and automatically configuration works in performance mode.
BENEFITS OF DATAGUARD ( or) ADVANTAGES OF DATAGUARD:
- High availability
- Disastor Recovery solution ( dr-solution)
- Switch over during plan maintenance
- Failover during un plan
- Stand by can be used for reporting purpose.
PRE REPRESENTS CONFIGURE DATAGUARD :
- Under laying hardware architecture should be same
- Version of Operating system , version of oracle including patch set level should be same
- Primary must and should run in Archive log mode .
- In case of maximum protection mode, it is mandatory to create stand by redo logs which are of the same size of primary redo logs.
ARCHITECTURAL COMPONENTS OF DATAGUARD:
- PRIMARY DATABASE: The production database that is used to create satndy by The Archive logs from the primary ndatabase are transferred and applied to standby databases.
- STAND BY DATABASE: The database on which we dependent in the event of primary collapse.
- ORACLE NETWORKING : Facilities moment of data from primary to standby
- LOG TRANSFORCE SERVICE: Services at primary which ships the data to the physical standby ( ARCH ,LGWR,LNS)
- LOG APPLYS SERVICE: Service at standby which applys the data to the standby database(MRP).
- DATA GUARD BROKER: Its optional component generally configured for fasters switch over with minimal commands. If we configured data guard with data guard broker DMON ( data guard monitor) process gets enabled .
- NETWORK TRANSMISSION MODE:
- Sync affirm
- A sync no affirm
In case of maximum protection mode , network transmission made should be “sync affirm”.
ARCHIVE LOG GAP RESOLUTION: In order resolve the archive log gap, oracle as introduced the parameters
FAL_SERVER ( FAL = FETCH ARCHIVE LOG)
DATA GUARD VIEWS:
V$DATA GUARD_ CONFIG
- If you want configure data guard , we required the license of ENTREPRISE EDITION
- Oracle golden gate is high performance hetrogeniese database replication technology , it requires separate license schema level.
> data guard is database level replication.
> in 10gr2 , oracle as introduced “ A SNOP SHOT STANDBY “ where we can open the standby database in read /write mode.
SNAP SHOT STAND BY:
- Can be opened in read /write mode.
- Both will not be in “sync”
- No extra license is required
- Can not be used for real time reporting
ACTIVE DATA GUARD:
- Can be opened in read only mode
- Both will be in sync
- Extra license is required
- Can be used for real time reporting.