Re: Tuning db_block_buffer

Hi,

I've seen this happen before too. Without any real technical explanation, I just assume that the hit ratio is not directly proportional to an increase in db_block_buffers. I had a buffer cache of approximately 300MB. As I increased this in 10MB increments, the hit ratio did not improve in relative increments, and on some occasions it may have actually dropped. The drop may have been due to an increase in users, usage, etc. After about 4 increments of 10MB, I increased the buffer cache to 600MB, and there was a huge increase in the hit ratio, to about 97% (from approx 75%).

This probably won't help much, but just an observation on my experience.

Regards,
Mick

John Chiu wrote:
>
> You have increase the sie of your data block buffer cache, it has more
> memory space to store the most recently used data ( more space for LRU
> data), thus reduce the frequency in cache out database data in the SGA, thus
> improve the hit ratio.
>
> HTH
>
> John Chiu
>
> <mayleel_at_my-deja.com> wrote in message news:848ds2$i0o$1_at_nnrp1.deja.com...
> > I'm running Oracle 8.0.5 on Solaris.
> >
> > I changed the db_block_buffer from 3200 to 4800,and my hit ratio went
> > from 78-80% to 50% and dropping!!!
> >
> > Any ideas?
> >
> >
> > Sent via Deja.com http://www.deja.com/
> > Before you buy.
Received on Fri Dec 31 1999 - 23:42:11 CST