Oracle buffer catch hit ratio is low.

[Former Member]

Hi,

We are facing problem with oracle buffer catch hit ratio problem in our quality system.

Often it falling down to below 50% and reaching to more then 90% with in few minutes.

"db_cache_size parameter value is 5008M". Is it suficent value or we need to increase it?

What may be the reasion for the temperary issue with buffer catch hit ratio?

Our "databse size aproximately 4 TB" and oracle is 11g R2 running on HP Unix.SAP is ECC6.

suggestions and solutions would be appriciated.

Thanks & Regards,

Ravindra.

[Former Member]

Classic!

databse size aproximately 4 TB

What about deleting some data? 5gb cache for 4tb data is kind of smallish...

Cheers Michael

[Former Member]

Hi Ravi,

First, check your free physical memory from ST06 (on DB host).

If you still have a lot of memory free, then you can increase your database buffer cache. Add some memory first. do not addd too much.

You can refer to my blog (http://sapbasis.wordpress.com) for some reading.

ardhian

http://inaroka.co.cc

http://basishowto.blogspot.com

[Former Member]

Make sure you have gone through the Note 1431798 - Oracle 11.2.0: Database Parameter Settings

[Former Member]

Hi Ravindra,

You can use "Oracle DB Cache Advise Monitor", in order to find out suitable value. You can find it under ST04 -> Performance -> Statistical Information -> SGA Monitor -> Cache advisory stat. -> Size of estimation

DB cache quality depends on table invalidations, db block changes, using not similar select statemens and so on. On the other hand, up and downs of the percentage of the buffer cache value is weird. It is really hard to say somethings without investigating to your system.

By the way, do not stuck buffer cache ratio value, because it may not reflect real performance of your database.

Best regards,

Orkun Gedik

[Former Member]

Hi Orkun Gedik

Thank you very much for the provided info, but i'm not able to find

ST04 -> Performance -> Statistical Information -> SGA Monitor -> Cache advisory stat. -> Size of estimation

navigation in ST04 transaction. Could you please elaberate it, our SAP version is ECC6.

Thanks in advance.

Thanks & Regards,

Ravindra

[Former Member]

Hi Ravindra,

Call ST04 transaction and browse Performance -> Statistical Information -> SGA Monitor -> Cache advisory stat. -> Size of estimation

I noted this path on ECC 6.0

Best regards,

Orkun Gedik