Online Consistent Backup

[Former Member]

Hi

I have been having some confusion about how online and online_cons backup works using BRTOOLS.

I am to understand that the online consistent backup is useful in cases where a database reset needs to be done to a certain "Point in Time".

Given a situation where

I have a database backup (online_cons) completed at 2PM and my database crashes at 5PM. Can I use my online consistent backup to bring the database state back to how it was at 2PM and then apply further offline redo log files between 2PM and 5PM

(assuming that I have all the log files which were generated between 2PM and 5PM)

Does this require manual effort in identifying the correct log sequence number or there a automated way like where I am prompted for a certain log sequence number?

I would appreciate if you could prompt me to sap note # which covers this.

Here is another conceptual question

In the case of an online backup

Does this backup the database + online redo logs + offline redo logs?

Does a log switch happen after the backup and NOT before the backup?

I am also trying to understand the benefits of the online backup over the online consistent backup (if I do have the backup of all the log files following the online consistent backup). I feel that restore time in case of the online consistent would be lesser than that of the online backup.

Please share your thoughts...

thanks

Ravi

[ashish_vikas]

HI Ravi,

 online_cons backup = datafile backup + backup of redologs generated in between backup runtime. 

So when you perform online_cons backup, you can recover db upto time when db backup finished, After that you need to apply all redologs generated. So yes if your database crashes at 5PM you can use my online consistent backup to bring the database state back to how it was at 2PM and then apply further offline redo log files between 2PM and 5PM.

In the case of an online backup
Does this backup the database + online redo logs + offline redo logs?

No Only database backup is performed which includes profile file, control file & BRTool profile files. No backup of online redo logs & offline redo logs

 Does a log switch happen after the backup and NOT before the backup?

Yes Log switch happens after after the backup. However Oracle performs Checkpoint before any tablespace enters backup mode.

As you can understand diff between online_cons backup & online backup, you can check benefits as per your requirements.

thanks

ashish