Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: Incomplete Recovery

Re: Incomplete Recovery

From: Howard J. Rogers <howardjr_at_www.com>
Date: Fri, 26 Jan 2001 15:55:42 +1100
Message-ID: <3a7104a8@news.iprimus.com.au>

Well, I hate to disagree, but a read-only tablespace is just fine for hot backups -on the grounds that its datafiles are entirely cold. The system will actually report an error if you try and put a read only tablespace into hot backup mode, on the grounds that since the header block is locked anyway, why bother?

You'll have to tell me why a read only tablespace cannot be reliably backed up hot, since I can't think of a single reason why that should be. Since no-one is writing to it, and checkpoint isn't updating it, the point is, I think, utterly moot.

Regards
HJR Jeremiah Wilton <jeremiah_at_wolfenet.com> wrote in message news:94quj4$s2b$1_at_nnrp1.deja.com...
> Stan,
>
> Just setting a tablespace to read only does not make it possible to
> reliably copy it with the database open. Just because you don't
> understand the internals of hot backup mode and why the files are
> written to during that time doesn't mean you shouldn't use it.
>
> Check out my article if you are uncomfortable with hot backup mode.
>
> http://www.wolfenet.com/~jeremiah/hot-backup.html
>
> If you copied the files by just setting the tablespaces read only, then
> there is no expectation that your restore/recover should work.
> Not even using my "clear the recovery checkpoint flag" incantation will
> do it any good.
>
> --
> Jeremiah Wilton
> http://www.wolfenet.com/~jeremiah
>
> si_bendovi_at_hotmail.com wrote:
> > Cold backup takes too long. What I was trying is to save time to
 restore
> > (copy) files. I found by making tablespace files read only that
 checkpoint
> > is made to file even when in backup mode. Error of CKPT process was:
> >
> > *** SESSION ID:(5.1) 2001.01.24.23.02.56.041
> > ORA-01110: data file 2: 'C:\SW\ORANT\DATABASE\USR1ORCL.ORA'
> > ORA-01114: IO error writing block to file 2 (block # 1)
> > ORA-27072: skgfdisp: I/O error
> > OSD-04008: WriteFile() failure, unable to write to file
> > O/S-Error: (OS 5) Access is denied.
> >
> > Since there is possible to do incomplete recovery to change only
 after file
> > is copied, I have to all the time recover to the last change, which I
 am
> > trying to avoid. I have no idea how Oracle handle consistency of those
> > tablespace files in case copy takes very long time!? I was thinking
 files
> > are not touched by server, but they having headers updated even in
 backup
> > mode!
> > I guess solution to this maid be what Jeremiah wrote:
> >
> > alter database recover database using backup controlfile until cancel;
> > (apply no logs)
> > alter database recover cancel;
> > alter database open resetlogs;
> >
> > I was using just command 'recover database' in server manager.
> >
> > Brian Peasland wrote:
> >
> > > I must be missing something here...
> > >
> > > To me the easiest way to revert to a state right before your test
 is to
> > > perform a cold backup of that system before you do the test. After
 the
> > > test, just restore everything from your cold backup. No worrying
 about
> > > complete/incomplete recovery and all that.
> > >
> > > si_bendovi_at_hotmail.com wrote:
> > > >
> > > > I am trying to have database running in backup mode to be
> > > > able to 'rollback' all transactions after backup mode was
> > > > started. Goal is to be able to put database to the same
> > > > state as it was before certain test. But I could not make
> > > > recovery done without complaining that system tablespace
> > > > needs more recovery. I am putting all tablespaces into
> > > > backup mode, running my tests and after that doing 'shutdown
> > > > abort'.
> > > >
> > > > recover until change (last change from v$backup);
> > > >
> > > > finish with warning, that system tablespace needs more
> > > > recovery. I could not figure out what it means more :-). Any
> > > > idea? Of course 'alter database open resetlogs' fails.
>
>
> Sent via Deja.com
> http://www.deja.com/
Received on Thu Jan 25 2001 - 22:55:42 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US