Re: Does Database Recovery really work?

Based on the sparse information in your note, If you copied the Oracle data files at the OS level while Oracle was up and running without the database being in archive log mode then the backup is not valid. If there was no update activity against the database when the copy was made it might work, but inconsistent objects could exist because Oracle uses lazy writes and could flush the buffers for work done earlier.

To do a hot backup requires being in archive log mode as you may need to apply updates to the files from the logs that were made for changes to the files, i.e., updates that took place to the file after the OS level copy started, but before the copy finished for a file.

You can take tablespaces offline and do cold backups of their files, but since you can not take the system tablespace offline this is a limited approach to backups, but is useful for some shops where forward recovery is not necessary as long as you do not lose the system tablespace.

The hot bu procedure is basically:
alter tablespace xxx begin backup
do OS level file copies
alter tablespace xxx end backup
when all tablespace are backed up - force switch of the redo log files backup the control file to backup_name
backup the archive files that correspond to the hot backup

simbl <simblit_at_yahoo.com> wrote in article <01bdc9b3$1dede1e0$a07015a5_at_pc160>...
> Could some Database recovery experts help to answer my question here?
>
> My physical file backup was done while the database was up and running. I
> do not have ARCHIVE LOG turned on.
> Files were *.dbf, *.ctl and *.rdo
>
> Did a restoration of the database and it gave an error on the
system01.dbf
> file, so i did a
> svrmgrl > recover database
> Then, The database started perfect, looks normal, no errors.
> I assume that there were not much activity (prob no activity) during the
> backup so the redo logs were used to reapply to the database during
> recovery. Everything looks normal but when I was doing my transaction
> query, some order by or group by statements, it gave some Internal error.

> Is the database in a correct state? Is there any tool I can use to verify
> it? How trustworthy is it?
>
> I've gone thru the Database Recovery class and theorically, this should
> work but now I have my doubts about the recovery.
> Can anyone advise on this? Greatly appreciate your help.
>
> Thanks,
> Cynthia
>
>
>
Received on Mon Aug 17 1998 - 08:04:17 CDT