Rolling forward the archivelog and online redo logs to the restored database

Question

Hi all,

I'm currently using Oracle db11g on Red Hat Enterprise Linux 5.0. I make an incremental level 0 one time a week and incremental level 1 everyday. I can restore this backup on my new Linux server without any problems because I have all archive logs generated after level 1 backup.

However, if online redo log is not yet filled (I mean that I have some redo info in the online log), how can I use this online log to roll forward to my restored database on the new Linux server? I don't want to lose the valuable information that is not yet archived.

Best regards, Sarith

Answer 1

So you mean you duplicate the database to another server using RMAN?

Online redo logs are only used for disaster recovery. For instance : you lose a datafile, restore the datafile from your latest backup, and apply archivelogs and finaly the online redo logs. This makes the restored datafile have the same SCN (System change number) as the controlfile (and other datafiles). Distaster recovery complete.

When you use your backups to duplicate the database on another server you can only roll forward using your archived logs. It does a incomplete recovery by defenition (creates a new controlfile and redologs).

Do a SQL> Alter system switch logfile before backup?

But no matter what restore is behind the source database if it stays open. I don't now your business case exactly but DataGuard might be an option for you.

Rob

Answer 2

Yes you can use the unarchived logs - if you applying the archive logs via "recover database using backup controlfile", just supply the redo log name instead of the suggested archive log name that the recovery process provides when it comes to that point (i.e. "runs out" of archive logs).

Answer 3

1. Restore your backed up files.
2. Copy your current online redo log files (from the "damaged" production instance) to the new server.
3. RECOVER DATABASE;

This scenario assumes you have total continuity with archived logs and online logs. In doing the recovery, Oracle will apply necessary archived redo, then move to the online redo logs to recover to the point of failure. Important! Don't restore online redo logs from the backup you have! Use the current online logs from your crashed instance.

Finally, don't believe anything you read without practicing it for yourself!