Re: Consistent export vs.snapshot too old.

While I agree that export is probably being used incorrectly here, I think we should clarify that using consistent=y does not ALWAYS require that every block of a particular ( or all ) schema's objects fit ( and stay ) in undo.

What is required is that all transaction activity during the export must remain available in the undo segments.

If you need to complete a consistent exp, you must ensure you are running it during your slowest period and that your undo segments are sized so that all transactions running concurrently with the export will "fit" in such a way that no wraps occur. This is, I admit, a tall order under heavy load.

-Kevin

"Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote in message news:taq4qo3aga0pa3_at_beta-news.demon.nl...
>
> "Jarek Palka" <jarek_at_kamsoft.com.pl> wrote in message
> news:3AACF264.164F3D85_at_kamsoft.com.pl...
> > During export of large database using parameter CONSISTENT=Y
> > we received an error :
> >
> > EXP-00056: ORACLE error 1555 encountered
> > ORA-01555: snapshot too old: rollback segment number 5 with name "RB14"
> > too small
> > EXP-00222:
> > System error message 1
> > System error message: No such file or directory
> >
> > Becouse database is on-line 24*7 lot of transactions was in-doubt during
> > this export. Is it possible to force export to use SELECTED
> > rollback_segment ?
> > How can we avoid such errors ?
> > --
> > ____________________________________________________________
> > Jaroslaw Palka <jarek_at_kamsoft.com.pl> P.I.KAMSOFT, Katowice
> > tel. (+48 32) 209-07-05, fax 209-07-15 POLAND
>
>
> By not using the consistent=y parameter, this requires the complete user
 or
> the complete database to fit in one rollback segment. You will *never*
> manage that.
> IMO (and Howard Rogers will support it) a 24*7 database means *Hot BACKUP*
> and archivelog. Period.
> export with consistent=y is not a viable replacement for a hot backup.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>
>
>
Received on Mon Mar 12 2001 - 13:03:20 CST