Re: db_block_buffers - can you have too many ? Thomas Kyte, please help!

Hooray, I'm not completely mad then.
The general consensus of the replies seems to be that a 60MB SGA on a 256MB NT box is too big ? 2 people have now said that I need to add more RAM to the box. But what's happening to the remaining 75% of my RAM ? The machine doesn't to anything else.. can NT really be stealing all that RAM for it's own mysterious purposes and swapping my SGA out ??
Thanks for all your replies but I have to say that I'm still a little sceptical
that we've really got to the bottom of what's going on here. Cheers anyway,

Richard.

satar_at_my-dejanews.com wrote in message <72db93$m33$1_at_nnrp1.dejanews.com>...
>I had a similiar experience, another DBA was evaluating my Database and
told
>me that I would have better performance if I lowered my db_block_buffers. I
>couldn't understand the logic behind it, so I didn't do it. My cache hit
>ratio is 99.97 percent, and I saw no tuning needs. I also wasn't paging or
>swaping and everything is fine and dandy. My question is, why would anyone
>suggest lowering the db_block_buffer parameter? My understanding was to
shove
>the whole database into the SGA whenever possible.
>
>Satar
>
>> > I had sudden performance problems - typical query
>> > response times up by a factor of 10. No change had been made to the
box and
>> > it's dedicated to Oracle.
>> >
>> > The database is quite large - 300 plus tables, and is heavily laden
with
>> > PLSQL code.
>> >
>> > With 256MB RAM on the box, I had increased db_block_buffers well above
the
>> > sample values shown in init.ora. (but still keeping the SGA size well
below
>> > total RAM - total SGA size was approx 60MB)
>> > Oracle support told me to reduce the db_block_buffers and this did
actually
>> > solve the problem !?
>> >
>> > Can anyone help me to explain this ? Surely the more database blocks
you
>> > can cached, the better so long as your OS isn't swapping the SGA to
disk ?
>> > Or am I missing something.
>>
>
>
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Received on Thu Nov 12 1998 - 03:55:33 CST