Log Buffer Size

[M.Shakeel Azeem]

i execute the following script
SQL> @c:\sga_statistics.sql;

PL/SQL procedure successfully completed.

SQL> set serveroutput on;
SQL> /
> SGA CACHE STATISTICS
> ********************
> SQL Cache Hit rate = 99.24
> Dict Cache Hit rate = 99.67
> Buffer Cache Hit rate = 99.88
> Redo Log space requests = 1440
>
> INIT.ORA SETTING
> ****************
> Shared Pool Size = 52428800 Bytes
> DB Block Buffer = 32768 Blocks
> Log Buffer = 20971520 Bytes
>
*** HINT: Log Buffer value is rather low!

should i have to increase the size of log_buffer Because Redo Log space requests = 1440 is high?
What u'll suggest Sir?
thanx in advance

[Thomasps]

Your log buffer is too big. What is your redo log file size? "Redo Log space requests" shows the number of times a user process wait for a redo log file not for buffer.

[M.Shakeel Azeem]

Your log buffer is too big. What is your redo log file size? "Redo Log space requests" shows the number of times a user process wait for a redo log file not for buffer.

we are having 3 redo log file of 1M
should i increase size to 20m and add 1 more redo file?

[pareshjavkar]

Hi,

I think increasing Redo Log size and Decreasing Log Buffer size might just help you.

Your Log_buffer is too big

[davey23uk]

1M? are you serious??

[Thomasps]

20MB Log buffer and 1MB Redo log file.. Funny..! And that is the origion of your problem.

Make 3 - 5 MB Log buffer and 25MB Log file atleast - Again depends on your Redo generation.

[pareshjavkar]

Dear Thomas,

What is advisable size of REdo Log file, if Redo generation for the day is around 15 for 100MB size.

[ixion]

Dear Thomas,

What is advisable size of REdo Log file, if Redo generation for the day is around 15 for 100MB size.

I'd leave your log file alone at 100mb... If the db is generating more than 1 archive file per say 10 - 20 minutes.. then its time to increase the size.

[KenEwald]

I'd leave your log file alone at 100mb... If the db is generating more than 1 archive file per say 10 - 20 minutes.. then its time to increase the size.

Not picking on you, but I'm genuinely curious, is the 10-20 minute window for reasonable recovery .. Ex. "can't afford to loose up to 20 minutes of transactions"?

What are the ramifications of time based vs. size based logging?

I've heard that the redo should be larger for RAC. Is that true?

Ken

[ixion]

20MB Log buffer and 1MB Redo log file.. Funny..! And that is the origion of your problem.

Make 3 - 5 MB Log buffer and 25MB Log file atleast - Again depends on your Redo generation.

Log buffer is still too big even at 3 MB...

Try starting out at 512K for you log buffer....