Re: Backup strategy

In article <3r47u6$6k8_at_homer.alpha.net>, sds_at_dataplusnet.com (Strategic Data Systems) wrote:

> I have followup question on the use of 'hot backups'.
>
> I am running Oracle 7.0.x on an IBM RS/6000 under AIX.
> If the put my tablespace in backup mode, and then proceed to backup the
> datafiles using my favorite UNIX backup utilitiy, do I get a 'good' backup
> of the datafile since there still is activity on the data file(s)?
>
> It would seem I would not, since I am backing up an ever changing file.
>

Scott,

You are correct that you are backing up an ever changing file. The file, by itself, is useless. While you were backing up the file, the database was writing extra information into the current online redo log file. If you need to recover that tablespace, you would need the backed up file, any archived and online redo log files that were written to during the backup (to "repair" the data file with inconsistent information), and any archived and online redo log files available to recover up to the point of failure.

The only physical difference between a data file backed up while the tablespace was in backup mode VS. a tablespaces that was in online mode is the number of the archive log (or is it the SCN) that is recorded in the file's header. This information is what clues Oracle into where in the redo log files to look for the possibly missing pieces of the transactions.

Matt... Received on Thu Jun 08 1995 - 00:00:00 CEST