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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <meta http-equiv="Content-Script-Type" content="text/javascript" /> <title>Setting the DBIO_EXPECTED Parameter</title> <meta name="generator" content="Oracle DARB XHTML Converter (Mode = ohj/ohw) - Version 5.1.1 Build 005" /> <meta name="date" content="2009-05-27T15:13:1Z" /> <meta name="robots" content="noarchive" /> <meta name="doctitle" content="Setting the DBIO_EXPECTED Parameter" /> <meta name="relnum" content="11g Release 2 (11.2)" /> <meta name="partnum" content="E10822-01" /> <link rel="copyright" href="./dcommon/html/cpyr.htm" title="Copyright" type="text/html" /> <link rel="stylesheet" href="./dcommon/css/blafdoc.css" title="Oracle BLAFDoc" type="text/css" /> <link rel="contents" href="toc.htm" title="Contents" type="text/html" /> <link rel="prev" href="tdppt_auto006.htm" title="Previous" type="text/html" /> <link rel="next" href="tdppt_auto008.htm" title="Next" type="text/html" /> <script src="./callback.js" type="text/javascript"></script> <noscript>Your browser does not support JavaScript. This help page requires JavaScript to render correctly.</noscript> </head> <body> <div class="zz-skip-header"><a href="#BEGIN">Skip Headers</a></div> <table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%"> <col width="86%" /> <col width="*" /> <tr valign="bottom"> <td align="left"></td> <td align="center"><a href="tdppt_auto006.htm"><img src="./dcommon/gifs/leftnav.gif" alt="Previous" /><br /> <span class="icon">Previous</span></a> </td> <td align="center"><a href="tdppt_auto008.htm"><img src="./dcommon/gifs/rightnav.gif" alt="Next" /><br /> <span class="icon">Next</span></a></td> </tr> </table> <p><a id="BABFIEGI" name="BABFIEGI"></a><a id="TDPPT024" name="TDPPT024"></a></p> <div class="sect2"><!-- infolevel="all" infotype="General" --> <h1>Setting the DBIO_EXPECTED Parameter</h1> <a name="BEGIN" id="BEGIN"></a> <p>ADDM analysis of I/O performance partially depends on a single argument, <code><a id="sthref63" name="sthref63"></a><a id="sthref64" name="sthref64"></a>DBIO_EXPECTED</code>, that describes the expected performance of the I/O subsystem. The value of <code>DBIO_EXPECTED</code> is the average time it takes to read a single database block, in microseconds. Oracle Database uses the default value of 10 milliseconds, which is an appropriate value for most hard drives. You can choose a different value based on the characteristics of your hardware.</p> <p class="orderedlisttitle">To determine the correct setting for the <code><span class="codeinlinebold">DBIO_EXPECTED</span></code> initialization parameter<a id="sthref66" name="sthref66"></a>: </p> <ol> <li> <p>Measure the average read time of a single database block for your hardware.</p> <p>This measurement must be taken for random I/O, which includes seek time if you use standard hard drives. Typical values for hard drives are between 5000 and 20000 microseconds.</p> </li> <li> <p><a id="sthref67" name="sthref67"></a><a id="sthref68" name="sthref68"></a>Set the value one time for all subsequent ADDM executions.</p> <p>For example, if the measured value is 8000 microseconds, then execute the following PL/SQL code as the <code>SYS</code> user:</p> <pre xml:space="preserve" class="oac_no_warn"> EXECUTE DBMS_ADVISOR.SET_DEFAULT_TASK_PARAMETER( 'ADDM', 'DBIO_EXPECTED', 8000); </pre></li> </ol> <div class="helpinfonotealso"> <h2>Related Topics</h2> <p><a href="tdppt_auto005.htm#CHDDFAGH">Configuring Automatic Database Diagnostic Monitor</a></p> </div> </div> <!-- class="sect2" --> <!-- Start Footer --> <div class="footer"> <table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%"> <col width="86%" /> <col width="*" /> <tr> <td align="left"><span class="copyrightlogo">Copyright © 2007, 2009, Oracle and/or its affiliates. All rights reserved.</span><br /> <a href="./dcommon/html/cpyr.htm"><span class="copyrightlogo">Legal Notices</span></a></td> <td align="center"><a href="tdppt_auto006.htm"><img src="./dcommon/gifs/leftnav.gif" alt="Previous" /><br /> <span class="icon">Previous</span></a> </td> <td align="center"><a href="tdppt_auto008.htm"><img src="./dcommon/gifs/rightnav.gif" alt="Next" /><br /> <span class="icon">Next</span></a></td> </tr> </table> </div> <!-- class="footer" --> </body> </html>
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