Private strand flush not complete how to find optimal size of redo log file

Question

hi,
i am using oracle 10.2.0 on unix system and getting Private strand flush not complete in the alert log file. i know this is due to check point is not completed.
I need to increase the size of redo log files or add new group to the database. i have log file switch (checkpoint incomplete) in the top 5 wait event.
i can't change any parameter of database. i have three redo log group and log files are of 250MB size. i want to know the suitable size to avoid problem.
select * from v$instance_recovery;
RECOVERY_ESTIMATED_IOS     ACTUAL_REDO_BLKS     TARGET_REDO_BLKS     LOG_FILE_SIZE_REDO_BLKS     LOG_CHKPT_TIMEOUT_REDO_BLKS     LOG_CHKPT_INTERVAL_REDO_BLKS     FAST_START_IO_TARGET_REDO_BLKS     TARGET_MTTR     ESTIMATED_MTTR     CKPT_BLOCK_WRITES     OPTIMAL_LOGFILE_SIZE     ESTD_CLUSTER_AVAILABLE_TIME     WRITES_MTTR     WRITES_LOGFILE_SIZE     WRITES_LOG_CHECKPOINT_SETTINGS     WRITES_OTHER_SETTINGS     WRITES_AUTOTUNE     WRITES_FULL_THREAD_CKPT
625     9286     9999     921600          9999          0     9     112166207               0     0     219270206     0     3331591     5707793please suggest me or tell me the way how to find out suitable size to avoid problem.
thanks
umesh

Answer 1

How often should a database archive its logs
Re: Redo log size increase and performance
Please read the above thread and great replies by HJR sir. I think if you wish to get concept knowledge, you should add in your notes.
"If the FAST_START_MTTR_TARGET parameter is set to limit the instance recovery time, Oracle automatically tries to checkpoint as frequently as necessary. Under this condition, the size of the log files should be large enough to avoid additional checkpointing due to under sized log files. The optimal size can be obtained by querying the OPTIMAL_LOGFILE_SIZE column from the V$INSTANCE_RECOVERY view. You can also obtain sizing advice on the Redo Log Groups page of Oracle Enterprise Manager Database Control."
Source:http://download-west.oracle.com/docs/cd/B13789_01/server.101/b10752/build_db.htm#19559
Pl also see ML Doc 274264.1 (REDO LOGS SIZING ADVISORY) on tips to calculate the optimal size for redo logs in 10g databases
Source:Re: Redo Log Size in R12
HTH
Girish Sharma