Hi There, sorry to hijack the thread but i picked up on a suggestion here. We have recently upgraded our Prod database to 10g and have noticed that at certain points of the day have been getting log switches every couple of minutes.
Our FAST_START_MTTR_TARGET parameter is set to 300
Our redo log groups were sized at 20MB and we increased to 40MB after noticing the high amount of switches but has had no effect.

I have just queried v$instance_recovery as suggested earlier in the thread and it says optimal log file size is 6GB!! Surely something is not right here with the size?

Code:
SQL> SELECT TARGET_MTTR,ESTIMATED_MTTR,WRITES_MTTR,WRITES_LOGFILE_SIZE, OPTIMAL_LOGFILE_SIZE FROM V$INSTANCE_RECOVERY;

TARGET_MTTR ESTIMATED_MTTR WRITES_MTTR WRITES_LOGFILE_SIZE OPTIMAL_LOGFILE_SIZE
----------- -------------- ----------- ------------------- --------------------
         27             11           0                   0                 6275