Re: online backup

Direct quote from Oracle Backup And Recovery Handbook 7.3 Edition from Oracle Press: "Note that when a tablespace is in hot backup mode, only some data structures in the data file header (or headers, if multiple dat a files exist for that tablespace) are updated, while the others are frozen. However, the contents of the file are current. For example, if an update is done on a table in this data file, the update is not blocked. But when a checkpoint is done, the checkpointed at SCN value is not written to the file header. This means that if a crash occurs during a hot backup, Oracle really needs to update only the file header and not the contents of the data file while opening the database.."

I guess the only thing that got frozen is the file header, but not the data.

Winnie Liu

In article <35D32BD3.5823_at_pharma.novartis.com>,   Devinder Pal Singh <Devinder_Pal.Singh_at_pharma.novartis.com> wrote:
> Marcus Reichardt wrote:
> >
> > Oracle stops writing to the data files, as otherwise a backup wouldn't
> > succeed, but it continues to write to redo logs.
> >
> > Marcus Reichardt
> > Consultant
> There is reaally a confusion there. At one place it says that all the
> changes to that datafile or tablespace in backup mode goto redo logs
> that is why more redo is generated. If some data in a block is chanaged
> then instead of that change going to the redo the whole block goes to
> redo. The question is does oracle stops writing to datafiles in backup
> mode and if it does then how these changes are refelected in the
> datafile and the other part is if it keeps on writing to the datafile in
> backup mode then that file can go out of sync with the backed up file.
> All thoughts are welcome
> Devinder
>

-----== Posted via Deja News, The Leader in Internet Discussion ==----- http://www.dejanews.com/rg_mkgrp.xp Create Your Own Free Member Forum Received on Thu Aug 13 1998 - 18:41:52 CDT