db buffer cache advisory clarification
- From: "Stephen Anderson" <st.anderson@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 28 Mar 2006 09:45:54 +0100
Can anyone let me know why the advisory is saying i can so drastically
reduce my PIO's by reducing my db_cache_size? I have looked around the web
and have never seen an explanation for this. I also looked on metalink to
see if it was a know bug.
This was from a lvl 5 statspack 15 minute snap on 9.2.0.3 on Sun Solaris.
The instance has been up for over 8 months. The results are the same no
matter when I snap.
Buffer Pool Advisory for DB: MERLIN Instance: MERLIN End Snap: 15
-> Only rows with estimated physical reads >0 are displayed
-> ordered by Block Size, Buffers For Estimate
Size for Size Buffers for Est Physical Estimated
P Estimate (M) Factr Estimate Read Factor Physical Reads
--- ------------ ----- ---------------- ------------- ------------------
D 16 .3 1,985 0.06 54,232,173
D 32 .5 3,970 0.03 28,255,991
D 48 .8 5,955 0.01 7,094,145
D 64 1.0 7,940 1.00 937,436,311
D 80 1.3 9,925 0.99 924,356,448
D 96 1.5 11,910 0.97 912,150,561
...
D 272 4.3 33,745 0.85 792,237,723
D 288 4.5 35,730 0.84 783,014,854
D 304 4.8 37,715 0.82 769,676,998
D 320 5.0 39,700 0.79 738,539,663
-------------------------------------------------------------
Regards,
Steve Anderson
Other related posts:
