Re: Low Hit Ratio

hardikarm_at_yahoo.com (Mahesh Hardikar) wrote in message news:<4a1c57c2.0301090023.14bbdfeb_at_posting.google.com>...
> Hi ,
>
> Oracle Version 8.1.7 on HP-UX 11 with 4GB RAM & 3 CPU's (540MHz).
> Machine Hosts Oracle Apps 11i & Database Server as well.
>
> Current settinngs in init.ora are :
>
> DB_BLOCK_BUFFERS 80000
> DB_BLOCK_SIZE 8192
> Shared_pool_size 382 MB
> Log_Buffer_size 10MB
> processes 750
> open cursors 900
> session cached cursors 900
> log_checkpoint_interval 100000
> sort_area_size 1024000
> db_writer_processes 3
> dbwr_io_slaves 3
> timed_statistics true
> cursor_space_for_time TRUE
>
> Current database size is around 48GB & database is in NOARCHIVELOG
> mode.
>
> We are experiencing low cache hit ratio like 60% in peak hours i.e.
> when users fire lot many reports.
>
> I wish to know if I have some room to increase DB_BLOCK_BUFFERS. 625
> MB SGA for 48GB DB seems low . But I want to know till how much can i
> raise it ? Since no of processes are ard 750, how much memory do they
> take in all ?
>
> Any advise on this is kindly appreciated ....
>
> Regards ,
> Mahesh Hardikar

Guideline is the complete SGA should stay below one third of physical memory or you will cause paging and swapping. You'd better off tuning your application. Too many people resolve application problems by throwing memory at the problem.

Sybrand Bakker
Senior Oracle DBA Received on Thu Jan 09 2003 - 15:59:29 CET