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Meaning of "Clearing online redo logfile" of source database in standby

user1151048
user1151048 Member Posts: 55 Blue Ribbon

Hi community,

We have a standby database setup on the same node as its source and when we started MRP, the alert log of the standby reported that the online redo logs of the source database were being "cleared", which appeared alarming, but had no impact to the source DB.  Can someone explain what is happening when this is reported or point me to some documentation explaining it?  I have not been able to find anything yet.

Here are some snippets from the standby alert log:

alter database recover managed standby database disconnect from session

...

Managed Standby Recovery not using Real Time Apply

Parallel Media Recovery started with 32 slaves

Waiting for all non-current ORLs to be archived...

All non-current ORLs have been archived.

Clearing online redo logfile 1 +PROD_DG/prod/onlinelog/group_1.711.941729641

Clearing online log 1 of thread 1 sequence number 144222

Completed: alter database recover managed standby database disconnect from session

Clearing online redo logfile 1 complete

Clearing online redo logfile 2 +PROD_DG/prod/onlinelog/group_2.714.941729647

Clearing online log 2 of thread 1 sequence number 144223

Clearing online redo logfile 2 complete

Clearing online redo logfile 3 +PROD_DG/prod/onlinelog/group_3.713.941729655

Clearing online log 3 of thread 1 sequence number 144220

Clearing online redo logfile 3 complete

Clearing online redo logfile 4 +PROD_DG/prod/onlinelog/group_4.736.941729661

Clearing online log 4 of thread 1 sequence number 144221

(continues...)

I have seen similar messages in standbys before but not where the specific logfile path is noted and not where that path is the source database.  The source and target databases have different disk groups and we are not using the log_file_name_convert parameter.   We are also not using standby redo logs as this is just a temporary copy to be used during an upgrade.

Thanks,

John

Answers