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<div>Hello Renar,</div>
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<div>Thank you for the suggestion. I tried the configuration changes. They however do not seem to have any effect - the performance seems identical. I also tried all 4 combinations. I checked the documentation on the parameter "dioSmallSeqWriteBatching" and
it states that small IOs are considered under 64kb. I've also found a parameter "dioSmallSeqWriteThreshold" but my GPFS version (5.1.9.0) claims that it's an unknown attribute.</div>
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<div><span>
<pre>-- <br></pre>
<div style="font-size: 9pt; color: rgb(89, 89, 89); font-family: verdana;">S přáním pěkného dne / Best regards</div>
<br style="caret-color: rgb(46, 52, 54); color: rgb(46, 52, 54);">
<div style="font-size: 11pt; color: rgb(220, 38, 30); font-family: verdana;"><b>Mgr. Peter Hruška</b><br>
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<div style="font-size: 9pt; font-family: verdana;"><font color="#595959">IT specialista</font><br>
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<div>On Mon, 2024-03-11 at 13:56 +0000, Grunenberg, Renar wrote:</div>
<blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex">
<div><font size="3" face="arial" color="red"><b>EXTERNÍ ODESÍLATEL</b><br>
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hallo Peter,<br>
my to cents to this.<br>
Set the diasbleDIO=yes Parameter to DEFAULT and use the <o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><br>
! dioSmallSeqWriteBatching 1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> disableDIO 0<br>
And give it a try.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><br>
Regards Renar<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div></div>
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<p></p>
<p><font style="font-family:Arial;">Renar</font> <font style="font-family:Arial;">Grunenberg</font><br>
<font style="font-family:Arial;">Abteilung Informatik - Betrieb</font><br>
<br>
<font style="font-family:Arial;">HUK-COBURG</font><br>
<font style="font-family:Arial;">Bahnhofsplatz</font><br>
<font style="font-family:Arial;">96444</font> <font style="font-family:Arial;">Coburg</font><br>
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<td><font style="font-family:Arial;"><font style="font-family:Arial;"><font style="font-family:Arial;">Telefon:</font></font></font></td>
<td><font style="font-family:Arial;"><font style="font-family:Arial;"><font style="font-family:Arial;">09561 96-44110</font></font></font></td>
</tr>
<tr>
<td><font style="font-family:Arial;"><font style="font-family:Arial;"><font style="font-family:Arial;">Telefax:</font></font></font></td>
<td><font style="font-family:Arial;"><font style="font-family:Arial;"><font style="font-family:Arial;">09561 96-44104</font></font></font></td>
</tr>
<tr>
<td><font style="font-family:Arial;"><font style="font-family:Arial;"><font style="font-family:Arial;">E-Mail:</font></font></font></td>
<td><font style="font-family:Arial;"><font style="font-family:Arial;">Renar.Grunenberg@huk-coburg.de</font></font></td>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Von:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gpfsug-discuss <gpfsug-discuss-bounces@gpfsug.org><b>Im Auftrag von
</b>Peter Hruška<br>
<b>Gesendet:</b> Montag, 11. März 2024 14:22<br>
<b>An:</b> gpfsug-discuss@gpfsug.org<br>
<b>Betreff:</b> [gpfsug-discuss] Slow performance on writes when using direct io<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">Hello,<o:p></o:p></p>
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<div>
<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<p class="MsoNormal">We encountered a problem with performance of writes on GPFS when the application uses direct io access. To simulate the issue it is enough to run fio with option direct=1. The performance drop is quite dramatic - 250 MiB/s vs. 2955 MiB/s.
We've tried to instruct GPFS to ignore direct IO by using "disableDIO=yes". The directive didn't have any effect. Is there any possibility how to achieve that GPFS would ignore direct IO requests and use caching for everything?<o:p></o:p></p>
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<div>
<p class="MsoNormal"><o:p> </o:p></p>
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<pre>-- <o:p></o:p></pre>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#595959">S přáním pěkného dne / Best regards<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Verdana",sans-serif;color:#DC261E">Mgr. Peter Hruška</span></b><span style="font-size:11.0pt;font-family:"Verdana",sans-serif;color:#DC261E"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#595959">IT specialista</span><span style="font-size:9.0pt;font-family:"Verdana",sans-serif"><o:p></o:p></span></p>
<div>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#595959">M Computers s.r.o.</span></b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#595959"><br>
</span><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#DC261E">Úlehlova 3100/10, 628 00 Brno-Líšeň (<a href="https://mapy.cz/s/gafufehufe" title="Click to open https://mapy.cz/s/gafufehufe"><span style="color:#0563C1">mapa</span></a>)</span><span style="font-size:9.0pt;font-family:"Verdana",sans-serif"><br>
<span style="color:#595959">T:+420 515 538 136</span><br>
<span style="color:#595959">E: </span><a href="mailto:peter.hruska@mcomputers.cz" title="Click to mail peter.hruska@mcomputers.cz"><span style="color:#0563C1">peter.hruska@mcomputers.cz</span></a><span style="color:#595959"><br>
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