Re: Does Database Recovery really work?

I don't think you can backup your physical file under noarchive log mode when the database is up and running. The header of that file may got updated in the middle of your backup. The data block in that file may got changed in the middle of the backup. Even if you are running under archive log mode, you still need to issue the alter tablespace <..> begin backup to put the tablespace to the backup mode so that the header of the file will not get updated during the hotbackup period!!

Okey.. I guess the reason that you can open the database and running is probably because of the header of the system01.dbf file is very recent and there are enough online redo log file to recover the database. For example, the header of your system01.dbf file from backup has log number 101. And the sequence number in your control file is 103. And you have the redo101.log and redo102.log and redo103.log files in your system. You can probably issue the recover database command to recover the database and open it. Since oracle will only check the header of all the datafiles and make sure that they are current and on sync and then you can open the database. But it does not guarantee that your datablock is not corrupt.

Winnie

simbl wrote in message <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 - 22:31:50 CDT