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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>John –<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Are the input and output files on the same disk subsystem, and
what kind of disk(s) is involved?<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>gdalwarp will run as a single task, so if it uses 1 processor
100% of the time you’ll see 25% utilization. If you run two gdalwarp jobs at
the same time, using the same disks, you can very easily cause disk thrashing
and bog the whole process down, so it’s not surprising to find two jobs in
parallel takes more than two jobs run serially.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>If possible, have the input and output files on different disks,
and avoid having read/write activity on the same disk or more than one job
writing to the same disk.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='margin-left:.75in;text-indent:-.25in;
mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>-<span
style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Ed<o:p></o:p></span></p>
<p class=MsoListParagraph style='margin-left:.75in'><span style='font-size:
11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Ed McNierney<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>President and Chief Mapmaker<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>TopoZone.com / Maps a la carte, Inc.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>73 Princeton Street, Suite 305<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>North Chelmsford, MA 01863<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Phone: 978-251-4242, Fax: 978-251-1396<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>ed@topozone.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
gdal-dev-bounces@lists.maptools.org
[mailto:gdal-dev-bounces@lists.maptools.org] <b>On Behalf Of </b>John Mitchell<br>
<b>Sent:</b> Monday, May 14, 2007 5:52 PM<br>
<b>To:</b> mitchelljj98@gmail.com; Gdal-Dev; MAPSERVER-USERS@lists.umn.edu<br>
<b>Cc:</b> Mark A Hollis<br>
<b>Subject:</b> [Gdal-dev] speeding up the gdalwarp process for mosaicing
andreprojection<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Hi,<br>
<br>
I have run the following gdalwarp command<br>
<br>
gdalwarp.exe -wo SKIP_NOSOURCE=YES -rc -s_srs EPSG:" + EPSG + "
-t_srs EPSG:" + EPSG_wgs84 + " -of HFA " + " -q " +
inputFiles + " " + outputFile <br>
<br>
against a group of geotiff files which both mosaics and reprojects them to
wgs84 and it works fine, but it takes 22:47 hours to generate the 52.89 GB
mosaic. <br>
Does anyone have any suggestions on how to speed up the gdalwarp process.
I have noticed that the 4 processor server is only being utilized between
14-26% across all 4 processors. Is their a way to force a higher
utilization of these processors? I have in past tried to run 2 gdalwarp
jobs simultaneously and I have noticed that it takes them much longer compared
to the total time when running serially (meaning one after the other). <br>
<br>
Thanks,<br>
<br clear=all>
<br>
-- <br>
John J. Mitchell <o:p></o:p></p>
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