<html><head><style type="text/css"></style></head><body><div style="font-family:arial,helvetica,sans-serif;font-size:12pt"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt;"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt;">Dear All,<br><br>I am going to install Oracle RAC on two Servers, With shared SAN storage (Servers and Storage is IBM)<br>OS = RHEL 5u5 x64 bit<br><br>And we used multipathing mechanism and created multipathing devices.<br>i.e. /dev/mapper/mpath1.<br><br>Then I created raw device /dev/raw/raw1 of this /dev/mapper/mpath1 Block device as per pre-reqs for Oracle Cluster.<br><br>Every thing looks good, But we faced the performance issue as under...<br><br>when we run command :<br>#dd if=/dev/zero of=/dev/mapper/mpath1 bs=1024 count=1000<br>the writing rate is approx. 34 MB/s<br><br>But If we run command<br>#dd if=/dev/zero of=/dev/raw/raw1 bs=1024 count=1000<br>the writing rate is very slow like 253 KB/s<br><br>Please advice how to tune the performance.<br><br><br><br><div> </div><p>Best Regards,<br></p><p style="text-indent: 0px; margin: 0px; color: rgb(179, 0, 179); font-size: 10pt; font-weight: 600;">Shariq Siddiqui</p><div style="font-family: times new roman,new york,times,serif; font-size: 14pt;"><font color="#00007f" face="verdana, helvetica, sans-serif" size="2"><a rel="nofollow" target="_blank" href="http://www.linkedin.com/in/shariqsiddiqui"><img alt="View Shariq Siddiqui's profile on LinkedIn" src="http://www.linkedin.com/img/webpromo/btn_liprofile_blue_80x15.gif" border="0" height="15" width="80"></a></font></div><font color="#00007f"><font face="verdana, helvetica, sans-serif"></font></font><p style="text-indent: 0px; margin: 0px; font-size: 10pt;"> </p><p style="text-indent: 0px; margin: 0px; font-size: 10pt;"> </p><div><br></div> </div><br> </div></div> </div><br> </body></html>