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Home -> Community -> Mailing Lists -> Oracle-L -> db buffer cache advisory clarification
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
-- http://www.freelists.org/webpage/oracle-lReceived on Tue Mar 28 2006 - 02:45:54 CST
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