Re: system tablespace rollback segment is corrupted in 8i or 9i

From: <fitzjarrell_at_cox.net>
Date: 6 Sep 2006 14:39:57 -0700
Message-ID: <1157578797.891731.145590@b28g2000cwb.googlegroups.com>

DA Morgan wrote:
> fitzjarrell_at_cox.net wrote:
> > DA Morgan wrote:
> >> fitzjarrell_at_cox.net wrote:
> >>
> >>> I'm not saying it, the Oracle documentation is stating this:
> >>>
> >>> "The Rollback Segment SYSTEM
> >>> Oracle creates an initial rollback segment called SYSTEM whenever a
> >>> database is created. This segment is in the SYSTEM tablespace and uses
> >>> that tablespace's default storage parameters. You cannot drop the
> >>> SYSTEM rollback segment. An instance always acquires the SYSTEM
> >>> rollback segment in addition to any other rollback segments it needs.
> >>>
> >>> With multiple rollback segments, Oracle tries to use the SYSTEM
> >>> rollback segment only for special system transactions and distributes
> >>> user transactions among other rollback segments. If there are too many
> >>> transactions for the nonSYSTEM rollback segments, then Oracle uses the
> >>> SYSTEM segment as necessary. In general, after database creation,
> >>> create at least one additional rollback segment in the SYSTEM
> >>> tablespace."
> >>>
> >>> I've recently added an extra SYSTEM rollback segment in our test
> >>> environments, to see what impact, negative or positive, it creates. I
> >>> can understand the logic of doing so; a second SYSTEM rollback segment
> >>> would allow an otherwise unavailable database to be mounted and opened,
> >>> as the second SYSTEM rollback segment can be used, so it could prevent
> >>> downtime in the event a SYSTEM rollback segment does become corrupted
> >>> or unusable.
> >>>
> >>>
> >>> David Fitzjarrell
> >> The link please ... the link. I want to capture this for my students.
> >>
> >> Thanks.
> >> --
> >> Puget Sound Oracle Users Group
> >
> > http://download-east.oracle.com/docs/cd/B10501_01/server.920/a96524/b_deprec.htm
> >
> >
> > David Fitzjarrell

>

> I followed your link and found it in 9.2 but I can not find the
> equivalent statement in the 10g docs. I've asked for a clarification
> from Oracle.

>

> Thanks for the link.
> --
> Puget Sound Oracle Users Group

I'm finding that the production systems won't allow me to create another SYSTEM rollback segment as they are in automatic undo mode. The test systems I've modified are not using automatic undo (for reasons unknown to me). I'm expecting to rectify that situation shortly, or at least discover why they're still using rollback segments.

I apologise for any confusion I (and the Oracle documentation for 9.2) may have created with this.

David Fitzjarrell Received on Wed Sep 06 2006 - 16:39:57 CDT