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<p class="MsoNormal"><span lang="en-IL" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Hi Michal,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="en-IL" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="en-IL" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">How are you ?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="en-IL" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="en-IL" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Can you also tell:<o:p></o:p></span></p>
<ol style="margin-top:0cm" start="1" type="1">
<li class="MsoListParagraphCxSpFirst" style="margin-left:0cm;mso-add-space:auto;mso-list:l4 level1 lfo8">
<span lang="en-IL" style="font-size:11.0pt;line-height:105%;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">How much luns are allocate for the GPFS File-System from Storage (minimum is 16) ?<o:p></o:p></span></li><li class="MsoListParagraphCxSpMiddle" style="margin-left:0cm;mso-add-space:auto;mso-list:l4 level1 lfo8">
<span lang="en-IL" style="font-size:11.0pt;line-height:105%;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">What is the Block-size defining in the GPFS FS ?<o:p></o:p></span></li><li class="MsoListParagraphCxSpMiddle" style="margin-left:0cm;mso-add-space:auto;mso-list:l4 level1 lfo8">
<span lang="en-IL" style="font-size:11.0pt;line-height:105%;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">How much pools you have in the FS ?<o:p></o:p></span></li><li class="MsoListParagraphCxSpLast" style="margin-left:0cm;mso-add-space:auto;mso-list:l4 level1 lfo8">
<span lang="en-IL" style="font-size:11.0pt;line-height:105%;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Does all tests are run on single server ?<o:p></o:p></span></li></ol>
<p class="MsoNormal" style="margin-top:12.0pt;text-autospace:none"><span lang="EN-US" style="font-family:"Arial",sans-serif;color:black">Regards<o:p></o:p></span></p>
<table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0" width="1464" style="width:1098.0pt;border-collapse:collapse">
<tbody>
<tr>
<td width="1464" colspan="4" style="width:1098.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" align="center" style="text-align:center;page-break-after:avoid;text-autospace:none">
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-top:12.0pt;page-break-after:avoid;text-autospace:none">
<span style="font-size:1.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
</td>
</tr>
<tr>
<td width="1464" colspan="4" style="width:1098.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-size:1.0pt;font-family:"Arial",sans-serif;color:black"> <o:p></o:p></span></p>
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<td width="606" colspan="2" style="width:454.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:blue">Yaron Daniel<o:p></o:p></span></p>
</td>
<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">94 Em Ha'Moshavot Rd<o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F"><img width="87" height="30" style="width:.9083in;height:.3083in" id="Picture_x0020_3" src="cid:image001.png@01DA5F86.FF6F94D0"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="606" colspan="2" style="width:454.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:blue">Storage and Cloud Consultant<o:p></o:p></span></p>
</td>
<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">Petach Tiqva, 49527<o:p></o:p></span></p>
</td>
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<td width="606" colspan="2" style="width:454.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-size:11.5pt;font-family:slack-lato;color:blue;background:#F8F8F8">Technology Services</span><span style="font-size:11.5pt;font-family:slack-lato;color:blue"><br>
<span style="background:#F8F8F8">IBM Technology Lifecycle Service</span></span><span style="font-family:"Arial",sans-serif;color:blue"><o:p></o:p></span></p>
</td>
<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">Israel<o:p></o:p></span></p>
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<td width="606" colspan="2" style="width:454.5pt;padding:0cm 0cm 0cm 0cm"></td>
<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F"> <o:p></o:p></span></p>
</td>
<td width="690" style="width:517.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black"> <o:p></o:p></span></p>
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</tr>
<tr>
<td width="90" style="width:67.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">Phone:<o:p></o:p></span></p>
</td>
<td width="516" style="width:387.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">+972-3-916-5672<o:p></o:p></span></p>
</td>
<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm"></td>
<td width="690" style="width:517.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Tms Rmn",serif;color:black"> </span><span style="font-family:"Tms Rmn",serif;color:black"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="90" style="width:67.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">Fax:<o:p></o:p></span></p>
</td>
<td width="516" style="width:387.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">+972-3-916-5672<o:p></o:p></span></p>
</td>
<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">
<o:p></o:p></span></p>
</td>
<td width="690" style="width:517.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Tms Rmn",serif;color:black"> </span><span style="font-family:"Tms Rmn",serif;color:black"><o:p></o:p></span></p>
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<tr>
<td width="90" style="width:67.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">Mobile:<o:p></o:p></span></p>
</td>
<td width="516" style="width:387.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">+972-52-8395593<o:p></o:p></span></p>
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<td width="168" style="width:126.0pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">
<o:p></o:p></span></p>
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<td width="690" style="width:517.5pt;padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Tms Rmn",serif;color:black"> </span><span style="font-family:"Tms Rmn",serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">e-mail:<o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F"><a href="mailto:yard@il.ibm.com">yard@il.ibm.com</a><o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Arial",sans-serif;color:#5F5F5F">
<o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Tms Rmn",serif;color:black"> </span><span style="font-family:"Tms Rmn",serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><span style="font-family:"Tms Rmn",serif;color:black"><a href="webex:%20%20%20%20%20%20%20%20%20%20%20%20https://ibm.webex.com/meet/yard"><span style="font-family:"Arial",sans-serif;color:blue;text-decoration:none">Webex:
</span><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:blue;text-decoration:none">https://ibm.webex.com/meet/yard</span></a></span><span style="font-family:"Arial",sans-serif;color:blue"><br>
<a href="webex:%20%20%20%20%20%20%20%20%20%20%20%20%20https://ibm.webex.com/meet/yard%0dIBM%20Israel"><span style="color:blue;text-decoration:none">IBM Israel</span></a><o:p></o:p></span></p>
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<p class="MsoNormal" style="page-break-after:avoid;text-autospace:none"><u><span style="font-family:"Arial",sans-serif;color:blue"><o:p><span style="text-decoration:none"> </span></o:p></span></u></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Aptos",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="en-IL" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt">From:</span></b><span lang="EN-US" style="font-size:11.0pt"> gpfsug-discuss <gpfsug-discuss-bounces@gpfsug.org>
<b>On Behalf Of </b>Michal Hruška<br>
<b>Sent:</b> Wednesday, 14 February 2024 20:29<br>
<b>To:</b> gpfsug-discuss@gpfsug.org<br>
<b>Subject:</b> [EXTERNAL] Re: [gpfsug-discuss] sequential I/O write - performance<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="mso-line-height-alt:.75pt"><span style="font-size:1.0pt;color:white">Dear friends, Thank you all for your time and thoughts/ideas! The main goal for sharing our test results comparing XFS and GPFS was to show, that the storage subsystem
is able to do better if the I/O is provided in different way. We were not <o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-line-height-alt:.75pt"><span style="font-size:1.0pt;color:white"></span><span style="font-size:1.0pt;font-family:"Aptos",sans-serif;color:white"><o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Dear friends,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Thank you all for your time and thoughts/ideas!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">The main goal for sharing our test results comparing XFS and GPFS was to show, that the storage subsystem is able to do better if the I/O is provided in different way.
We were not trying to compare XFS and GPFS directly, we understand that there will be some performance drop using GPFS (compared to “raw” performance) but we are just surprised by the ~20-25% performance drop.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">We tried to change multiple suggested parameters but we got no performance gain. As there was no change we tried to do more troubleshooting
using different configurations.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">To better understand what we tried I have to describe our environment a bit more:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Our underlying storage system is IBM FS7300 (each controller has 384 GB cache). There are 8 DRAIDs (8+2+1). Each DRAID has its own pool
and each pool has one Volume (LUN). Every FE server (we have 3 of them) is connected directly to this storage using two 32 GFC connections. 3 client servers and FE servers are connected to LAN switch using 100GbE connection.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Testing results (metadata are located on NVMe SSD DRAID):<o:p></o:p></span></p>
<ol style="margin-top:0cm" start="1" type="1">
<li class="MsoListParagraphCxSpFirst" style="margin-left:0cm;mso-add-space:auto;mso-list:l2 level1 lfo3">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">We used second - identical storage to test the performance but we are getting almost the same results compared to first storage. In iohist we can see that one LUN (dm-device)
is probably overloaded as IO time is high – from 300 to 500 ms. <o:p></o:p></span></li><li class="MsoListParagraphCxSpMiddle" style="margin-left:0cm;mso-add-space:auto;mso-list:l2 level1 lfo3">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">Using both storage systems together in one big FS (GPFS): always is only one dm-device slow (according to iohist output) but the “problematic” dm-device changes in time.<o:p></o:p></span></li><li class="MsoListParagraphCxSpMiddle" style="margin-left:0cm;mso-add-space:auto;mso-list:l2 level1 lfo3">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">During out tests we also tried synchronous fio test but we observed significant performance drop.<o:p></o:p></span></li><li class="MsoListParagraphCxSpLast" style="margin-left:0cm;mso-add-space:auto;mso-list:l2 level1 lfo3">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">We tried to compare single LUN performance GPFS against XFS: GPFS 435MB/s compared to XFS 485MB/s. From single server. The drop is not so significant but when we added more
LUNs to the comparison the performance drop was more painful.<o:p></o:p></span></li></ol>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">For this testing “session” we were able to gather data by Storage Insights to check storage performance:<o:p></o:p></span></p>
<ol style="margin-top:0cm" start="1" type="1">
<li class="MsoListParagraphCxSpFirst" style="margin-left:0cm;mso-add-space:auto;mso-list:l1 level1 lfo6">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">There is no problematic HDD – the worst latency seen is 42ms from all 176 drives in two storage systems. Average latency is 15ms.<o:p></o:p></span></li><li class="MsoListParagraphCxSpMiddle" style="margin-left:0cm;mso-add-space:auto;mso-list:l1 level1 lfo6">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">CPU usage was at 25% max.<o:p></o:p></span></li><li class="MsoListParagraphCxSpMiddle" style="margin-left:0cm;mso-add-space:auto;mso-list:l1 level1 lfo6">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">“Problematic” DRAID latency – average is 16ms the worst is 430ms. I can not tell if there was the same peak in latency during XFS tests but I think that no (or not so bad)
– as the XFS is able to perform better than GPFS. <o:p></o:p></span></li><li class="MsoListParagraphCxSpLast" style="margin-left:0cm;mso-add-space:auto;mso-list:l1 level1 lfo6">
<span lang="EN-US" style="font-size:11.0pt;line-height:105%;mso-fareast-language:EN-US">During our tests the write cache for all pools was fully allocated. Both for XFS and GPFS tests. Which is expected state as the cache is much faster than HDDs and it should
help organize writes before they are forwarded to RAID groups.<o:p></o:p></span></li></ol>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Do you see some other possible problems we missed?
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">I do not want to leave it behind “unfinished” but I am out of ideas.
</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Segoe UI Emoji",sans-serif;mso-fareast-language:EN-US">😊</span><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">Best,<br>
Michal<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="CS" style="font-size:11.0pt;mso-fareast-language:CS">From:</span></b><span lang="CS" style="font-size:11.0pt;mso-fareast-language:CS"> Michal Hruška
<br>
<b>Sent:</b> Thursday, February 8, 2024 3:59 PM<br>
<b>To:</b> 'gpfsug-discuss@gpfsug.org' <<a href="mailto:gpfsug-discuss@gpfsug.org">gpfsug-discuss@gpfsug.org</a>><br>
<b>Subject:</b> Re: [gpfsug-discuss] sequential I/O write - performance<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">@Aaron<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">Yes, I can confirm that 2MB blocks are transfered over.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">@ Jan-Frode<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">We tried to change multiple parameters, but if you know the best combination for sequential IO, please let me know.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">#mmlsconfig<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">autoload no<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">dmapiFileHandleSize 32<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">minReleaseLevel 5.1.9.0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">tscCmdAllowRemoteConnections no<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">ccrEnabled yes<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">cipherList AUTHONLY<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">sdrNotifyAuthEnabled yes<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">pagepool 64G<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">maxblocksize 16384K<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">maxMBpS 40000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">maxReceiverThreads 32<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">nsdMaxWorkerThreads 512<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">nsdMinWorkerThreads 8<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">nsdMultiQueue 256<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">nsdSmallThreadRatio 0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">nsdThreadsPerQueue 3<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">prefetchAggressiveness 2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">adminMode central<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">/dev/fs0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">@Uwe<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US">Using iohist we found out that gpfs is overloading one dm-device (it took about 500ms to finish IOs). We replaced the „problematic“ dm-device (as we have enough drives
to play with) for new one but the overloading issue just jumped to another dm-device.<br>
We believe that this behaviour is caused by the gpfs but we are unable to locate the root cause of it.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="CS" style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#595959;mso-fareast-language:CS">Best,<br>
Michal<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="CS" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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