rollback segment too old

hello ,
I know this question has been posted in this forum a lot of times and i have read most of them from the archives but still can anybody help me out with this.

Most of the activities on our system are short queries and updates and there are no batch files doing doing huge updates/selects that are running.

initially i had 10 rollback segements with 512K of initial,next and 5M of optimal. and the statistics that i used to get from v$rollstat was this

   EXTENTS WRITES GETS WAITS OPTSIZE HWMSIZE SHRINKS WRAPS AVESHRINK
---------- ---------- ---------- ---------- ---------- ---------- ----------

• ---------- 6 10416 301 0 364544 0 0 0 11 93479584 303442 0 5242880 5627904 0 212 0 11 171553042 358345 20 5242880 93179904 18 390 4864000 11 93410072 346803 42 5242880 5627904 0 213 0 11 94937792 304325 2 5242880 5627904 0 216 0 11 89638294 301663 2 5242880 5627904 0 204 0 11 169077244 340748 3 5242880 100859904 19 400 5012210 11 90504356 303184 0 5242880 5627904 0 206 0 11 91587584 303244 1 5242880 5627904 0 209 0 11 118358574 315595 3 5242880 37371904 7 276 4534857 11 96496414 303315 1 5242880 5627904 0 219 0

and i used to get the snapshot too old error

after this i changed the rollback segment parameters to intial 1M, next 1M, optimal 50M and minextent 20 maxextent 400 Isn't this supposed to reduce the wraps? but now i get these statistics from v$rollstat

   EXTENTS WRITES GETS WAITS OPTSIZE HWMSIZE SHRINKS WRAPS AVESHRINK
---------- ---------- ---------- ---------- ---------- ---------- ----------

• ---------- 6 9750 300 0 364544 0 0 0 20 223812724 631736 1 52428800 21295104 0 534 0 20 223707032 673188 29 52428800 21295104 0 534 0 20 224711684 632845 2 52428800 21295104 0 537 0 50 310731946 663666 2 52428800 102510592 5 637 9859891 50 223743564 631558 0 52428800 53243904 0 534 0 20 224872176 632430 2 52428800 21295104 0 538 0 50 223026560 629640 1 52428800 53243904 0 532 0 20 223153556 628883 1 52428800 21295104 0 532 0 50 223274594 654880 17 52428800 53243904 0 533 0 50 351965640 690660 3 52428800 121401344 7 688 9736777

if you can see, the wraps have more than doubled. and as expected i am still getting ora-1555

what should i do for this.

warm regards,
Pinto. Received on Fri Jun 21 2002 - 00:40:44 CDT