Re: Consistent export vs.snapshot too old.

"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)

FWIW, I certainly do. I like export as an *adjunct* to physical backups. I certainly wouldn't ever want to rely on exports-only as a recovery mechanism.

Consistent=Y strikes me as being like 'pctincrease' -one of those lovely ideas that allows the software vendor to tick of a features list, but is of dubious practical value. Before it will work, conditions have to be 'just right' (low load, big rollback segments etc etc etc). I reckon hot backups are easier -all you need is a good redo sub-system to keep up with the redo stream generated. The worst that can happen is your system grinding to a temporary halt as ARCH, LGWR and DBWR catch up -at least the damn thing doesn't keel over on a regular basis with a fatal 1555 error!

Regards
HJR
>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 Tue Mar 13 2001 - 02:52:03 CST