I don't think buffered I/O is going to help you. For any files associated with the database, including archived redo logs, you want the data written to the disk (physically or in a protected cache) when the OS tells Oracle that the I/O write request is complete. Even with a buffered file system, Oracle will buffer the reads, but "write through" the buffer for writes to make sure the data is really on disk. Find out what type of disks the archivelog dest file system is built on. Then work with your SA or storage engineer to provide you with dedicated disks, add spindles, or move to a RAID implemention that handles writes more efficiently (say RAID 5 -> RAID 1+0). John Smiley Technical Management Consultant TUSC, Inc. On 6/23/05, Radoulov, Dimitre <cichomitiko@(protected)> wrote: > > Thanks, > the problem is that now I'm working on a system with direct IO activated > on the log_archive_dest filesystem (the SA told me that this was the > workaroud for previous "performance problems") > OS: Solaris 8 > Oracle: 8.1.7.4 <http://8.1.7.4/> > OFA(including log_arch_dest): vxfs fstype > mount output: > /smsp_ofa on /dev/vx/dsk/osmspdg/smsp_ofa > read/write/setuid/mincache=direct/convosync=direct/delaylog/largefiles /ioerror=mwdisable/dev=449022b > > ... and it's now that the arch processes are really not able to keep up > with the log file switches: "cannot allocate new log" messages + shutdown > abort from the SUN Cluster fault monitor for timeout ... > So I was wondering, could the direct IO be beneficial for the > log_archive_dest filesystem in some cases? > Cheers > Dimitre > > -- -- Original Message -- -- > *From:* John Smiley <jrsmiley@(protected)> > *To:* cichomitiko@(protected) > *Cc:* oracle-l@(protected) > *Sent:* Thursday, June 23, 2005 5:36 PM > *Subject:* Re: Q: Filesystem choice for log_archive_dest > > As long as your archiver processes are able to keep up with the log file > switches, it doesn't matter what type of filesystem they're on. If you start > seeing the archiver lag behind, or worse, you system comes to a screeching > halt because it can't perform a log switch, you can increase the number of > archive log processes (if the disks supporting the log archive dest(s) can > handle more load) or store the archive logs on faster I/O. Typically this > takes the form of LUNs on a RAID 1+0 using your file system of choice. For > best performance, give the archivelogs their own set of disks. > John Smiley > Technical Management Consultant > TUSC, Inc. > > On 6/23/05, Radoulov, Dimitre <cichomitiko@(protected)> wrote: > > > > Hi, > > could anyone provide guidelines for the log archive destination > > filesystem's/IO type choice (both MS and *nix solutions would be > > interesting)? > > Thanks, > > Dimitre > > > >
<div>I don't think buffered I/O is going to help you. For any files associated with the database, including archived redo logs, you want the data written to the disk (physically or in a protected cache) when the OS tells Oracle that the I/O write request is complete. Even with a buffered file system, Oracle will buffer the reads, but "write through" the buffer for writes to make sure the data is really on disk. </div> <div> </div> <div>Find out what type of disks the archivelog dest file system is built on. Then work with your SA or storage engineer to provide you with dedicated disks, add spindles, or move to a RAID implemention that handles writes more efficiently (say RAID 5 -> RAID 1+0). </div> <div> </div> <div>John Smiley</div> <div>Technical Management Consultant</div> <div>TUSC, Inc.<br> </div> <div><span class="gmail_quote">On 6/23/05, <b class="gmail_sendername">Radoulov , Dimitre</b> <<a href="mailto:cichomitiko@(protected)">cichomitiko@(protected)< /a>> wrote:</span> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0 .8ex; BORDER-LEFT: #ccc 1px solid"> <div><font face="Arial" size="2">Thanks,</font></div> <div><font face="Arial" size="2">the problem is that now I'm working on a system with direct IO activated on the log_archive_dest filesystem (the SA told me that this was the workaroud for previous "performance problems") </font></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2">OS: Solaris 8</font></div> <div><font face="Arial" size="2">Oracle: <a onclick="return top.js.OpenExtLink (window,event,this)" href="http://8.1.7.4/" target="_blank">8.1.7.4</a></font>< /div> <div><font face="Arial" size="2">OFA(including log_arch_dest): vxfs fstype < /font></div> <div><font face="Arial" size="2">mount output:</font></div> <div><font face="Arial" size="2">/smsp_ofa on /dev/vx/dsk/osmspdg/smsp_ofa read /write/setuid/mincache=direct/convosync=direct/delaylog/largefiles/ioerror =mwdisable/dev=449022b </font></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2">... and it's now that the arch processes are really not able to keep up with the log file switches: "cannot allocate new log" messages + shutdown abort from the SUN Cluster fault monitor for timeout ... </font></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2">So I was wondering, could the direct IO be beneficial for the log_archive_dest filesystem in some cases? </font ></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2"></font><font face="Arial" size="2"></font> <font face="Arial" size="2"></font><font face="Arial" size="2"></font> < /div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2">Cheers</font><br><span class="sg">Dimitre < /span></div> <div><span class="e" id="q_104a9f1b978f28c0_3"> <div> </div> <div> </div> <blockquote style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <div style="FONT: 10pt arial">-- -- Original Message -- -- </div> <div style="BACKGROUND: #e4e4e4; FONT: 10pt arial"><b>From:</b> <a title= "jrsmiley@(protected)" onclick="return top.js.OpenExtLink(window,event,this)" href ="mailto:jrsmiley@(protected)" target="_blank">John Smiley</a> </div>
<div style="FONT: 10pt arial"><b>To:</b> <a title="cichomitiko@(protected)" onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:cichomitiko @(protected)" target="_blank">cichomitiko@(protected)</a> </div> <div style="FONT: 10pt arial"><b>Cc:</b> <a title="oracle-l@(protected)" onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:oracle-l @(protected)" target="_blank">oracle-l@(protected)</a> </div> <div style="FONT: 10pt arial"><b>Sent:</b> Thursday, June 23, 2005 5:36 PM</div> <div style="FONT: 10pt arial"><b>Subject:</b> Re: Q: Filesystem choice for log _archive_dest</div> <div><br> </div> <div>As long as your archiver processes are able to keep up with the log file switches, it doesn't matter what type of filesystem they're on. If you start seeing the archiver lag behind, or worse, you system comes to a screeching halt because it can't perform a log switch, you can increase the number of archive log processes (if the disks supporting the log archive dest(s) can handle more load) or store the archive logs on faster I/O. Typically this takes the form of LUNs on a RAID 1+0 using your file system of choice. For best performance, give the archivelogs their own set of disks. </div> <div> </div> <div>John Smiley</div> <div>Technical Management Consultant</div> <div>TUSC, Inc.<br><br> </div> <div><span class="gmail_quote">On 6/23/05, <b class="gmail_sendername">Radoulov , Dimitre</b> <<a onclick="return top.js.OpenExtLink(window,event,this)" href ="mailto:cichomitiko@(protected)" target="_blank">cichomitiko@(protected) </a>> wrote:</span> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0 .8ex; BORDER-LEFT: #ccc 1px solid"> <div><font face="Arial" size="2">Hi,</font></div> <div><font face="Arial" size="2">could anyone provide guidelines for the log archive destination filesystem's/IO type choice (both MS and *nix  ;solutions would be interesting)?</font></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2"></font> </div> <div>Thanks,<br>Dimitre </div> <div> </div> <div> </div></blockquote></div><br></blockquote></span></div></blockquote> </div><br>
