Re: Split Blocks on Instance Crash

BEGIN/END does not avoid split blocks.
It merely caused the generation of more redo to recover from split blocks.

From the Oracle Recovery Manager Users Guide, in the section on Fractured Blocks:

When performing open backups *without* using RMAN, you must put tablespaces in *backup mode* in case the operating system reads a block for a backup that is currently being written by the database writer. When not in backup mode, Oracle records only changed bytes in the redo stream, not whole blocks. When a tablespace is in backup mode, Oracle writes the before-image of each changed block in the tablespace to the redo log before modifying it. Then, Oracle also records the changes to the block in the redo log. When you recover using SQL*Plus, Oracle applies the blocks and changes during recovery, so it does not matter that the block in the backup was fractured.

HTH Jared

On 12/22/05, Charlotte Hammond wrote:
>
>
> Thanks David - but why is this different from the
> backup situation? You would have the (archived) redo
> available then too, but you must still use BEGIN/END
> BACKUP to avoid split blocks.
>
> Charlotte
>
>
>
> --- David Sharples wrote:
>
> > because the information is available from redo /
> > undo and can easily be
> > replayed in case of a failure
> >
> > On 12/22/05, Charlotte Hammond
> > wrote:
> > >
> > > Hi All,
> > >
> > > Why does instance crash recovery not encounter the
> > > split blocks that you might get doing a backup
> > without
> > > BEGIN/END BACKUP?
> > >
> >
>
>
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--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist