direct IO
- From: Laimutis.Nedzinskas@xxxxxx
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 25 Nov 2010 17:32:02 +0200
Looking for experiences/advices of others regarding one issue with direct
IO.
Recently we switched to another data center and some databases reported
increased IO time.
After investigating we found that IO is slower on file systems (Veritas,
Solaris 10) mounted with direct io options.
AWR shows more time on scattered reads but for the same number of blocks
too.
We are going to switch of direct IO and test but for the time beeing I am
wandering why direct IO is bad in our case.
We've got seriously increased times for statistics gathering which does
full scan naturally - we've found 2 full scan sqls on the same table
clearly comming from dbms_stats package . Full scan is not cached by
oracle. But file system cache can help in that particular case.
Any thoughts are wellcomed on this issue.
Thank you in advance, Laimis N
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