How to keep multiple Undo segments online

Hi Oracle gurus,

I have a question on Undo. Is there any way to fix 20 Undo segments online when the database starts up?

When the Oracle 9i database starts up, 10 undo segments automatically get online as:

     Wed Sep  7 04:41:55 2005
     Undo Segment 1 Onlined
     Undo Segment 2 Onlined
     Undo Segment 3 Onlined
     Undo Segment 4 Onlined
     Undo Segment 5 Onlined
     Undo Segment 6 Onlined
     Undo Segment 7 Onlined
     Undo Segment 8 Onlined
     Undo Segment 9 Onlined
     Undo Segment 10 Onlined

Every now and then additional Undo segments get automatically online as:

     Fri Sep  9 14:56:04 2005
     Undo Segment 11 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 12 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 13 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 14 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 15 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 16 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 17 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 18 Onlined
     Fri Sep  9 14:56:04 2005
     Undo Segment 19 Onlined

Then again they get offline as:

     Fri Sep  9 16:57:33 2005
     SMON offlining US=11
     SMON offlining US=12
     SMON offlining US=13
     SMON offlining US=14
     SMON offlining US=15
     SMON offlining US=16
     SMON offlining US=17
     SMON offlining US=18
     SMON offlining US=19

Making onlining/offlining these Undo segments slows the database down for a minute or two, and I have been looking for a way to fix this. So far I have downloaded several Oracle pdf manuals; however, haven't yet found solutions to this particular issue.

The following information is the spec I manage:

*OS : AIX 5.2 (oslevel -r 5200-04)
*Database : Oracle 9i (9.2.0.5.0)
*Database use : OLTP
*undo_management : AUTO
*Undo_retention : 10800
*Undo_supress_errors : TRUE
*Undo_tablespace : UNDO01
*Undo table space size : 5GB

Any advice is highly appreciated.

Thanks in advance,

alea Received on Fri Sep 09 2005 - 03:46:57 CDT