rollback segments and performance

From: Pankaj Asundi <asundi_at_flash.net>
Date: Fri, 03 Sep 1999 16:01:22 GMT
Message-ID: <37CFF034.3ECC885C@flash.net>

Hi Guys/Gals: I am facing some performance degradation while running our application on Oracle 8.0.4. Here are some of the results of my initial test. Can some one clue me on where to look next and what else could I optimize.

Our RBS are as follows. We have 4 rbs all configured the same way. rbs0&1 reside in one tablespace and rbs2&3 in a different tablespace.

CREATE PUBLIC ROLLBACK SEGMENT RBS3
    TABLESPACE RBSCAGE
    STORAGE(INITIAL 250K

            NEXT 250K
            MINEXTENTS 16
            MAXEXTENTS 4090
            OPTIMAL 25M);

ALTER ROLLBACK SEGMENT RBS3 ONLINE; As you can see we have a very high number of writes, shrinks and wraps into the rbs. Does high number of writes affect system performance, I know Shrinks and Wraps do. And by setting the optimal size higher that 25M, it might take care of that, but not very sure.

RBS         Writes             Gets                 Waits
Extents             Shrinks         Wraps
RBS0     702169130     3287704             8593
200                     267            7834
RBS1     865357712      3110048             6888
103                         8             9892
RBS2     915158202      3419537             6240
200                         0             0443
RBS3     586222166      3479309             93532
103                     325             7492

The application processing is taking longer as more and more data is read in.

All this activity is happening on a single drive except the redo log files are on a different drive.

Let me know if you have any pointers for us. Thanks

Pankaj Received on Fri Sep 03 1999 - 11:01:22 CDT