Re: Snapshot too old during stress test... how to avoid

From: <Jared.Still_at_radisys.com>
Date: Wed, 04 Jun 2003 15:05:00 -0800
Message-ID: <F001.005AA935.20030604150500@fatcity.com>

... and if it still doesn't work, use the trick of putting a transaction in
each of the rollback segments while the system is otherwise quiesced, and *do not* commit or rollback the transactions.

This forces the rollbacks to extend if necessary, they will never wrap back to the first extent ( actually the second) as long as those transactions
are not committed.

It just uses a lot of disk space. Disk is cheap, right? :)

Consider offlining all your production RBS and creating temporary ones that you can easily drop later.

I've used it with SAP client copies, which will not run to completion without
doing this, at least on our system.

Jared

Kirtikumar Deshpande <kirtikumar_deshpande_at_yahoo.com> Sent by: root_at_fatcity.com
 06/04/2003 09:45 AM
 Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        Re: Snapshot too old during stress test... how to avoid

Try removing optimal setting, and shrinking RBS to the min extents (or even below) before running
your tests.

• Kirti
  • Garry Gillies <g.gillies_at_weir.co.uk> wrote:
    > From memory (of a course attended looong ago),
    > Oracle recommends one rollback segment for every
    > three to four users.
    > Four rollback segments between thirty six processes
    > does seem a little mean.
    >
    > Garry
    >
    >
    >
    >
    >
    > <rgaffuri_at_cox.net>
    > Sent by: root_at_fatcity.com
    > 04/06/03 13:59
    > Please respond to ORACLE-L
    >
    >
    > To: Multiple recipients of list ORACLE-L
    <ORACLE-L_at_fatcity.com>
    > cc:
    > Subject: Snapshot too old during stress test... how to
    avoid
    >
    >
    > Im testing worst case scenarios right now. So Im doing batch
    > updates,inserts,deletes and 'create table as' from a staging tablespace
    of
    > approximately 5GBs to a master tablespace of approximately 11GBs.
    >
    > Ive got my job queue processes set to 36 and Im running 36 at a time in
    > the background in order to gather statistics and timing under worst case
    

> scenarios.
>
> Im in 8.1.7.3 and I have increased the size of my RBS tablespace to 11GB

> for this test. I have 4 standard RBS with optimal size set to 1GB. Why
> would I get a snapshot too old? I would think that 11GBs of rollback
would
> be big enough. Would increasing the number of Rollback segments avoid
this
> even though I have the same amount of space in the tablespace?
>
> In reality Im going to seriallize the process to avoid this and to
improve
> performance, however, I want to stress the system.
>
> any advice?
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: <rgaffuri_at_cox.net
> INET: rgaffuri_at_cox.net
>
 

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Author: Kirtikumar Deshpande
  INET: kirtikumar_deshpande_at_yahoo.com

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  INET: Jared.Still_at_radisys.com

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Received on Wed Jun 04 2003 - 18:05:00 CDT