db file scattered read and readv() system call

From: Dba DBA <oracledbaquestions_at_gmail.com>
Date: Fri, 31 Jul 2009 16:00:23 -0400
Message-ID: <f30139790907311300i1a0ea3e8y47bb108766bfb240_at_mail.gmail.com>

Jeff Holt wrote a paper that is on hotsos where he stats that Oracle does a readv() system call. We are having physical IO issues where in one system on the same hardware response time is several times faster than on another for similiar volumes. When we look at the disk activity on SAN we do not see any bottlenecks.

Does anyone have any information about happens when Oracle issues a readv() call to what happens when it gets down to the SAN layer? Is there a paper someone would recommend that is readable to a now hardware engineer?

Also, do you know any tools to trace an oracle db file scattered read -> readv() -> san while I am running a test? Similiar to a 10046 trace but take it down to the SAN layer?

Received on Fri Jul 31 2009 - 15:00:23 CDT

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