Re: More online backup questions

Yes, Oracle writes to the data blocks of the tablespace while it is in backup mode. This is called a 'fuzzy' backup.

When you restore from a hot backup, your data will not be consistent. Your database will not startup until you also 'recover' it.

After the restore of the hot backup data files, you 'recover' the database by using the redo logs (from the archives, if necessary) to roll forward to a point in time where the database is again consistent.

The oldest possible point of consistency is the point-in-time just after the last tablespace was END BACKUP. It there is a chance that you may need to recover to a point-in-time that happened to be in the middle of a hot backup, you will need to restore the prior hot backup and recover forward. So I would never purge my archive log backups until I had at least two backups.

We actually keep our data file backups and our archive log backups for 42 days to allow time to go back to a prior month end.

Roy Brokvam wrote:

> Dear Oracle friends,
>
> I think many of the aspects of online backup are poorly documented. Maybe I
> haven't looked in the right places? Anyway, hopefully, you know the answers
> to some of my questions.
>
> In Oracle 7.3.4, between ALTER TABLESPACE ... BEGIN BACKUP and ALTER
> TABLESPACE ... END BACKUP, does DBWR write to the tablespace datafiles? If
> it does, do you have a not-too-long explanation of how this is handled at
> recovery? I mean, Oracle can't possibly know which datafiles/parts of a
> datafile that I have already copied, can it?
>
> The v$backup view reports the backup status of datafiles. Am I right in
> saying that all datafiles belonging to the same tablespace must have the
> same status? If so, why does the v$backup view report per datafile, and not
> per tablespace?
>
> Does the control file contain information about backup status (in
> particular, the time of backup) of datafiles/tablespaces? If so, should I
> also backup the control file after partial backups?
>
> Can I delete archived log files after successful online backup of all
> tablespaces? If so, I guess that the most recent achived log file that I may
> delete, is the file with sequence number 1 less than oldest online log
> sequence number before I start the first partial backup?
>
> Grateful for any help.
>
> Regards,
>
> Roy Brokvam
> roy.brokvam_at_conax.com
Received on Wed Apr 07 1999 - 20:23:10 CDT