Been lazy (& bussy) for past couple of weeks with new implementations on Rman Catalog , AS & others ......
So continuing with the discussion on DR .....
Some of the biggest question faced when implementing a DR are :
- What Kind of standby - physical or logical
- What king of Protection mode
- What to use - Log Writer or Archiver
Here is a small table to help you make a better decesion :
Mode | Log Writing Process | Network Trans Mode | Disk Write Option | Redo Log Reception Option | Supported on |
Maximum Protection | LGWR | SYNC | AFFIRM | Standby redo logs are required | Physical standby databases |
Maximum Availability | LGWR | SYNC | AFFIRM | Standby redo logs | Physical and logical standby databases |
Maximum Performance | LGWR or ARCH | ASYNC if LGWR | NOAFFIRM | Standby redo logs | Physical and logical standby databases |
Physical Standby : is a exact replica of Primary DB , it uses redo apply technique & has to be open in "Read only" mode .
Logical Standby : uses SQL apply technique & is in read-write mode as it can also hold addtional objects for reporting use .
One of the reasons people opt for physical standby is that logical standby has some limitations when it comes to objects , so before proceding to logical one should always check weather all his objects can be supported in Logical standby .
in couple of days i will describr the process of implementing DR (both logical & Physical).....keep watching the blog ..
