Re: Crazy mistake in "Oracle Unleashed"

From: <satar_at_my-dejanews.com>
Date: Wed, 30 Sep 1998 20:51:24 GMT
Message-ID: <6uu5kc$c97$1@nnrp1.dejanews.com>

I guess I was under the wrong impression in regards to online backup of datafiles. Thanks to everyone who replied to the post.

Satar

In article <6utuii$397$1_at_nnrp1.dejanews.com>, satar_at_my-dejanews.com wrote:
> John,
> read my post...Modified blocks are written to the REDO LOGS. After the END
> BACKUP is issued and at the next log switch, the changed blocks are then
> updated in the datafiles. It is such an easy concept to grasp, yet so many
> DBA's are confused about this procedure. Maybe I'm wrong, but I would hate to
> believe that I paid $1400 dollars to Oracle Education to mislead me on Backup
> and Recovery.
> Satar Naghshineh
> In article <36115B13.89938F9D_at_deere.com>,
> "John P. Higgins" <jh33378_at_deere.com> wrote:
> > <HTML>
> > It is true: Oracle stops updating file headers durring backup mode.
> >
> > It is also true: Oracle writes changed blocks to the files durring backup
> > mode.
> >
> > satar_at_my-dejanews.com wrote:
> > <BLOCKQUOTE TYPE=CITE>OK, I think everyone is confused. According to
> "Oracle7:Backup
> > and Recovery
> > Volume Two * Student Guide" which I obtained durring my DBA Master's
> > program
> > held by Oracle Corporation, on page 10-13 through page 10-17 it tells
> > you the
> > following: After you administer BEGIN BACKUP...This action suspends
> > updates
> > to the header block of each database file belonging to the Tablespace.
> > If a
> > log switch occures, the sequence number information is updated as shown.
> > A
> > record is also written to the active redo log file to indicate that
> > an online
> > backup has begun. END BACKUP...This action will cause the header blocks
> > for
> > the datafiles belonging to the tablespace to be updated at the next
> > log
> > switch. If a log switch occures, the sequence number information is
> > updated
> > as shown. * The time between the ALTER BEGIN and ALTER END commands
> > should be
> > minimized, as more redo information is generated and written to the
> > redo log
> > files durring the backup since modified blocks are written to the redo
> > log
> > files. * Prior to Oracle7 release 7.2, any instance faliur while an
> > online
> > backup was in progress could cause the subsequent automatic recovery
> > at
> > startup to fail due to the header on the backed up file being frozen.
> > Oracle7
> > at startup would then detect that the header was out of sync with the
> > rest of
> > the files, and startup would fail with the message the file needed
> > recovery.
> > New to release 7.2, you can allow an online backup to be ended before
> > opening
> > the database after a system failure, by executing the ALTER DATABASE
> > DATAFILE
> > END BACKUP command.
> Oracle DBA/UNIX System Admin
> Advanced Enterprise Solutions
> (949) 756-0588
> Oracle Re-Seller
>
> -----------== Posted via Deja News, The Discussion Network ==----------
> http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
>

--
Oracle DBA/UNIX System Admin
Advanced Enterprise Solutions
(949) 756-0588
Oracle Re-Seller

-----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own Received on Wed Sep 30 1998 - 15:51:24 CDT