Re: Backup questions

Hi,

<vikasa_at_despammed.com> a écrit dans le message news: sl2ibt4pm54th4q8ig5be9jlcghs3luppb_at_4ax.com...
> Would appreciate help with the following backup/recovery related
> issues:
>
> 1. During online backup, when a tablespace is marked as BEGIN BACKUP,
> any changes to that tablespae are recorded in the redologs. When the
> END BACKUP is issued, does Oracle read the redologs and apply these
> changes to the actual datafile(s) of the tablespace? Or does it just
> stay in the redolog?

When the END BACKUP is issued, all the changes made during backup are applied on the tablespace.

>
> 2. After issuing a BEGIN BACKUP and during copying the tablespace's
> datafile, there is a disk failure and the datafile is lost. How does
> one recover in this case?

You would need to restore a previous backup of this file and apply all archived logs since then.
The begin backup doesn't help you there.

>
> 3. If I need to recover only a few datafiles and not the entire
> database, I would do RECOVER DATAFILE <datafile>. What happens in this
> case? Does Oracle ignore the redo entries which pertain to the other
> datafiles?

Yes, it only applies changes made to this particular tablespace, all the other changes are ignored.

>
> Under what situation would I need to do ALTER DATABASE DATAFILE <file>
> OFFLINE DROP?

If you have moved all the objects from that file to another one, and you don't want it anymore.
Maybe also in case of a transportable tablespace, but the command might be issued at tablespace level (i'm not sure).

>
> Once I do this, how can I bring the datafile online again?
You can if it is a transportable tablespace. Else, you would have do recreate the datafile, but you would lose all data.

>
> Thanks...

Hope I helped.

Matthieu Darnet Received on Wed Mar 21 2001 - 16:19:19 CST