Re: Online Backup Doubt

Well, all the Control File trace file does is to list the physical locations of the data files. So when run, Oracle is able to run off to those locations, check the headers of the data files found there, and find the highest SCN it can. That must be the most recent part of the database, and everything else must be synchronised to it.

So then it creates the controlfile(s), and forces into the controlfile header the highest SCN previously found. And then, now we're in the mount state, it simply issues the 'recover database' command.

If you look at the trace script, all of that is there -the script even contains the 'recover database' bit for you. All you have to do is make sure you restore the various bits of your hot backup to the appropriate locations (ie, the ones mentioned in the script file itself) -or edit the script so that it points to the new locations you've chosen to restore to.

Regards
HJR "J Jacob" <jenijacob_at_hotmail.com> wrote in message news:f88104c0.0201012224.1c4e0f18_at_posting.google.com...
> Hi,
>
> This one is an interesting observation. May be anybody else around who
> have solaris also can try it out.
>
> The usage of trace files to bring up hot db backup, I guess it's
> possible. But not sure how. May be Howard can help on this.
>
> Cheers
> J Jacob
>
> kunjaathi_at_hotmail.com (Augustine Joseph) wrote in message
news:<bde72cc6.0112302129.3f4e979a_at_posting.google.com>...
> > Hi,
> >
> > I made a mistake when I mentioned about DB restoration. What I
> > actually meant was I've tried "DB recovery".
> >
> > I've tried a DB recovery and I got "... needa media recovery" when my
> > backup script has got the 'host copy ..' statement which was executed
> > inside the oracle. That's how I assumed the backup has been invalid.
> >
> > I've done few tests and I'm very much sure that the problem was there.
> > But what I don't understand why this DB file was not synhcronised.
> >
> > Below is how I tested.
> >
> > My Original script(Backup was invalid in this case, prompted for the
> > media recovery for system01.dbf)
> >
> > svrmgrl <<EOF
> > connect internal
> > alter tablespace SYSTEM begin backup;
> > host `cp -p /u01/datafiles/DB/system01.dbf /u02/backup/DB/.`
> > alter tablespace SYSTEM end backup;
> > ....................
> > quit
> > EOF
> >
> >
> > My test script (This time system01.dbf was OK. But the next DB file
> > tools01.dbf
> > prompted for media recovery, for which 'copy' was executed within
> > oracle)
> >
> > svrmgrl <<EOF
> > connect internal
> > alter tablespace SYSTEM begin backup;
> > quit
> > EOF
> > cp -p /u01/datafiles/DB/system01.dbf /u02/backup/DB/.
> >
> > svrmgrl <<EOF
> > connect internal
> > alter tablespace SYSTEM end backup;
> >
> > alter tablespace tools begin backup;
> > .....
> >
> > quit
> > EOF
> >
> > Regarding the control trace file I'm confused. If I've a hot backup
> > and control trace, and say all my control files been corrupted, can
> > you please suggest what are the steps I need to follow to recreate the
> > control files and bring up the DB?
> >
> > Tx
> > Augustine
> >
> >
> >
> >
> >
> > "Howard J. Rogers" <dba_at_hjrdba.com> wrote in message
news:<3c2f64e9$0$2599$afc38c87_at_news.optusnet.com.au>...
> > > Restoring a backup doesn't test anything, apart from your abilities to
issue
> > > appropriate restore commands. The real test comes when Oracle
proclaims
> > > that "file X is inconsistent and needs media recovery"... if you are,
at
> > > that point, unable to apply archives/redo to the file to make it
consistent,
> > > and can't thereafter issue the 'alter database open' command then
sure, the
> > > file was toast. But if you get the 'media recovery complete' message,
and
> > > are then able to open the database successfully, it would suggest the
file
> > > was fine.
> > >
> > > If you read my original reply again, you'll notice that the discussion
about
> > > when the tracefile backup of the controlfile is useful contained not
one
> > > mention of hot or cold backups. The question of whether to take the
trace
> > > version as opposed to the binary version backup is a matter of the
eventual
> > > use that can be made of each version during a recovery scenario.
Either
> > > method works fine hot or cold. The trace script is useful for those
rare
> > > occasions when all multiplexed versions of the controlfile are lost or
are
> > > corrupt; the binary backup is useful for when user errors result in a
> > > physical alteration to the database (such as inadvertently dropping a
> > > tablespace). You should do both.
> > >
> > > Regards
> > > HJR
> > > --
> > > ----------------------------------------------
> > > Resources for Oracle: http://www.hjrdba.com
> > > ===============================
> > >
> > >
> > > "Augustine Joseph" <kunjaathi_at_hotmail.com> wrote in message
> > > news:bde72cc6.0112292010.6a9c3b00_at_posting.google.com...
> > > > Hi,
> > > >
> > > > The trace file is useful in the case of cold backup. Is it corrct?
> > > >
> > > > ">> I'd be interested to know how you *know* the backup is invalid."
> > > >
> > > > I tested the backup by restoring it.
> > > >
> > > > Tx
> > > > Augustine
> > > >
> > > >
> > > > "Howard J. Rogers" <dba_at_hjrdba.com> wrote in message
> > news:<3c2e3cbd$0$5269$afc38c87_at_news.optusnet.com.au>...
> > > > > Comments below
> > > > > HJR
> > > > > --
> > > > > ----------------------------------------------
> > > > > Resources for Oracle: http://www.hjrdba.com
> > > > > ===============================
> > > > >
> > > > >
> > > > > "Augustine Joseph" <kunjaathi_at_hotmail.com> wrote in message
> > > > > news:bde72cc6.0112282014.40efabf3_at_posting.google.com...
> > > > > > Hi,
> > > > > >
> > > > > > 1) For online backup is it mandatory that the 'backup
controlfile' be
> > > > > > executed at the end of the backup process. I mean after all the
> > > > > > tablespacess are backed up.
> > > > > >
> > > > >
> > > > > Nothing is "mandatory". It's up to you whether you want a backup
of
> > your
> > > > > control file -which happens to be just as an intrinsic part of
your
> > database
> > > > > as the datafile/tablespaces you've carefully backed up.
Commonsense
> > would
> > > > > suggest that you *should* take a backup of it, though whther
that's a
> > binary
> > > > > backup or atrace file backup is more open to discussion.
Personally,
> > I'd
> > > > > recommend nightly trace file backups and weekly binary ones. The
point
> > > > > being is that the trace file version is an extremely easy way of
> > recovering
> > > > > from total controlfile loss, but the binary version is useful if a
> > > > > tablespace ever gets dropped.
> > > > >
> > > > > > 2) I've this statement in my unix script(Solaris)
> > > > > >
> > > > > > Alter tablespace AJAPP begin backup;
> > > > > > host`cp /u01/datafiles/db/aj.dbf /bkp/datafiles/aj/aj.dbf`
> > > > > > Alter tablespace AJAPP end backup;
> > > > > >
> > > > > > does the oracle waits the copy to be completed before proceeds
with
> > > > > > the 'alter' statement.
> > > > >
> > > > > I rather think it depends on Unix. Al I can tell you is that, on
> > Windows
> > > > > 2000, if you have a SQL script containing the lines...
> > > > >
> > > > > alter tablespace system begin backup;
> > > > > host copy d:\oracle\oradata\db2\system01.dbf d:\backup1.dbf
> > > > > alter tablespace system end backup;
> > > > >
> > > > > ...then SQL Plus performs the actions synchronously, waiting for
each
> > one to
> > > > > finish before moving on to the next (meaning the backup is useful
and
> > > > > valid). I can't comment as to whether Solaris works the same
way -though
> > > > > it's not difficult to knock up a three-line script and then run it
> > within
> > > > > SQL Plus and watch to see what happens. If this is a *shell*
script
> > you're
> > > > > running, and not a SQL script, someone who knows the O/S will have
to
> > > > > comment.
> > > > >
> > > > > >I'm getting invalid online backup. My doubt is
> > > > > > here.
> > > > > >
> > > > >
> > > > > I'd be interested to know how you *know* the backup is invalid.
> > > > >
> > > > > Regards
> > > > > HJR
> > > > >
> > > > >
> > > > >
> > > > > > If i come out of oracle(svrmgrl) after alter begin statement and
does
> > > > > > a OS copy, backup is valid.
> > > > > >
> > > > > > Any ideas?
> > > > > >
> > > > > > Thanks
> > > > > > Augusitne
Received on Wed Jan 02 2002 - 13:53:31 CST