[thesite] oracle tuning..

Daniel J. Cody djc at starkmedia.com
Wed Aug 22 12:18:36 CDT 2001

this is mostly for dean or any other oracle heads out there..

i noticed the front page was taking a while to load after I dropped the 
new RAM in there, and did some poking around.. it turns out our buffer 
cache hit rate was down at like 15% because the db_block_buffers were 
set insanely low..

i played with it a bit, and ended up setting db_block_buffers to 3200 
and db_files up to 400(from 80)

the buffer cache is hitting about 99.8% right now(after 30 minutes) as a 
result.. also the 'getarticles' query on the front page is now just 
under 2 seconds to build, down about 3 seconds.

so, everything seems ok, but the only thing i'm concerned about
  is oracle's total lack of thirst to use more than 200Mb of memory. now 
i don't know if this is just because its been running for a short period 
of time or because the buffer recycle is high(which isn't a bad thing) 
or what.. linux is also caching about 128Mb of RAM. its still got 450+Mb 
of physical *free*, which i think is a bit wacky.

so i guess what i'm getting at is ya, the pages are a ton faster now out 
of the DB. but did i set the buffer cache to hit *TOO* often(and is 
there such a thing as too many cache hits(cus i wouldnt think so)?)?

anyways, whenever you get a minute, let Jr. DBA here know :)



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