Re: Hotbackups & Redo Logs

[This followup was posted to comp.databases.oracle.server and a copy was sent to the cited author.]

In article <34F109E1.A004CD9A_at_ibm.net>, randy_prater_at_ibm.net says...
> I am familiar with using hot backups with Oracle and have used them to
> recover a tablespace but I have one question for anyone unlucky enough
> to have had this experience.
>
> When you take a hot backup you get a copy of all your data files, your
> archive logs, and a "backup" version of your control file. The only
> files not backed up are your redo log files. This raises a question.
>
> If you are in a disaster situation where you have no database at all to
> start with and you only have your hot backup (with no redo logs backed
> up) how do you deal with the fact that the redo logs are not there after
> you restore this hot backup from tape?
>
> I'll be experimenting with this on a test database but want to know if
> anyone else has been here before and what you did.

What the user is wondering in the post is what happens to the redolog.dbf files that are NOT backed up during hot backups.

It is true, you do not have to backup these files. You have backed up your datafiles, control files, and archive logs. There are two scenarios, a) simple recovery of a damaged datafile and b) full system recovery for the purposes of disaster recovery.

Simple recovery of damaged datafiles does not imply loss of the redolog datafiles. However, disaster recovery is the scenario the user is questioning how these datafiles get recreated? The redologs get recreated when you are RESETING the redologs in a disaster recovery scenario, which will recreate the logfile *.dbf files.

Hope this helps.

• Neil