Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: system tablespace rollback segment is corrupted in 8i or 9i

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

From: DA Morgan <damorgan_at_psoug.org>
Date: Wed, 06 Sep 2006 16:32:56 -0700
Message-ID: <1157585573.264950@bubbleator.drizzle.com>


fitzjarrell_at_cox.net wrote:

> 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

No need to apologize. It was good to have a look at it. I have sent a copy to the tech writer responsible for it and hope to hear something back. My suspicion is that the doc will be corrected but who can say. ;-)

-- 
Puget Sound Oracle Users Group
Received on Wed Sep 06 2006 - 18:32:56 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US