AI and BI files

[sureshp]

1. please explain waht is
BEFORE IMAGE file
AFTER IMAGE file.
2. what is the use of these files.

 

[TomBascom]

The BI file is the "UNDO log". It is used to back out transactions.

The AI file (actually a series of archived ai extents...) is the "REDO log". It is used to "roll forward" transactions against a backup in order to recover a database.

BI is mandatory. There is no way around it. Even the -i option (no-integrity) writes bi notes, just in a less recoverable manner.

AI is optional -- you have to set it up and configure it. While it is technically optional no one should ever run a production database without it. It is a DBA's best friend and it is negligent and irresponsible to not be running after-imaging.

 

[comatt1]

The BI file is the "UNDO log". It is used to back out transactions.

The AI file (actually a series of archived ai extents...) is the "REDO log". It is used to "roll forward" transactions against a backup in order to recover a database.

BI is mandatory. There is no way around it. Even the -i option (no-integrity) writes bi notes, just in a less recoverable manner.

AI is optional -- you have to set it up and configure it. While it is technically optional no one should ever run a production database without it. It is a DBA's best friend and it is negligent and irresponsible to not be running after-imaging.

AI is optional (mandatory to keep a job), but is also one of those things that need to be configured and tested heavily; especially pre-10.1B (whenever AIARCHIVER was added).

10.1B makes a DBA's life much easier (especially since the AI notes can be verified after they are created, and not have to be loaded onto another server to verify they are good).

So setting it up incorrectly is even more irresponsible

 

[sureshp]

thanks for your explanations