<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Hi Rosana,</div><div class=""><br class=""></div><div class="">Without knowing anything about your setup or test, my first question would be whether you accounted for caching between your read tests? That can occur at several layers within the environment, including the client, server, and underlying storage hardware. This is naturally a benefit when in production, but needs to understand during performance testing. And I’m assuming that your file system was not otherwise utilized during your tests. Another assumption would be that the file system was mostly empty so that file fragmentation and disk seeks weren’t a problem.</div><div class=""><br class=""></div>—Rick<div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Nov 23, 2017, at 10:52 AM, Rosana Guimaraes Ribeiro <<a href="mailto:rosana_guimaraes_@hotmail.com" class="">rosana_guimaraes_@hotmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div id="divtagdefaultwrapper" dir="ltr" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class=""><p style="margin-top: 0px; margin-bottom: 0px;" class=""></p><div style="margin: 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">Hi,</div><div style="margin: 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class=""><br class=""></div><div style="margin: 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">I have some doubts about Lustre, I already sent my issues to forums but no one answer me.</div><div style="margin: 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">In our application, during the performance testing on lustre 2.4.2 we got times of reading and writing to test I/O operations with a file of almost 400GB. <br class="">Running this application a lot of times, consecutively, we see that in write operations, I/O time remain on same range, but in read operations there are a huge difference of time. As you can see below:</div><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">Write time <span class="x_error">[sec]</span>:<br class="">325.77<br class="">318.80<br class="">325.44<br class="">458.54<br class="">316.89<br class="">327.75<br class="">344.90<br class="">340.34<br class="">383.57<br class="">316.35</p><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">Read time <span class="x_error">[sec]</span>:<br class="">570.48<br class="">601.11<br class="">447.14<br class="">406.39<br class="">480.44<br class="">5824.40<br class="">299.40<br class="">293.54<br class="">1049.93<br class="">4190.47</p><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">We ran on the single client with 1 process and tested on same infrastructure (hardware and network).<br class="">Could you explain why is reading time so distorted? What kind of problem might be occurring?</p><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class=""><br class=""></p><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">Regards,</p><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class="">Rosana</p><p style="margin: 10px 0px 0px; padding: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; font-size: 14px;" class=""><br class=""></p><p style="margin-top: 0px; margin-bottom: 0px;" class=""></p></div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">lustre-discuss mailing list</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="mailto:lustre-discuss@lists.lustre.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">lustre-discuss@lists.lustre.org</a><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org</a></div></blockquote></div><br class=""></div></body></html>