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Simon,</div>
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Thanks for the quick response and related information! We are at least at v5.0.5 so we shouldn't see much exposure to this issue then.</div>
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<span style="font-family:Arial,sans-serif; font-size:13.3333px">Thanks,</span><br>
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<b><span style="margin:0px; font-size:10pt; font-family:Arial,sans-serif; color:black">Oluwasijibomi (Siji) Saula</span></b></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> gpfsug-discuss-bounces@spectrumscale.org <gpfsug-discuss-bounces@spectrumscale.org> on behalf of gpfsug-discuss-request@spectrumscale.org
<gpfsug-discuss-request@spectrumscale.org><br>
<b>Sent:</b> Tuesday, June 22, 2021 10:56 AM<br>
<b>To:</b> gpfsug-discuss@spectrumscale.org <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> gpfsug-discuss Digest, Vol 113, Issue 19</font>
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Today's Topics:<br>
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1. GPFS bad at memory-mapped files? (Saula, Oluwasijibomi)<br>
2. Re: GPFS bad at memory-mapped files? (Simon Thompson)<br>
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----------------------------------------------------------------------<br>
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Message: 1<br>
Date: Tue, 22 Jun 2021 15:17:16 +0000<br>
From: "Saula, Oluwasijibomi" <oluwasijibomi.saula@ndsu.edu><br>
To: "gpfsug-discuss@spectrumscale.org"<br>
<gpfsug-discuss@spectrumscale.org><br>
Subject: [gpfsug-discuss] GPFS bad at memory-mapped files?<br>
Message-ID:<br>
<PH0PR08MB659898B39A0CE6434B98C18998099@PH0PR08MB6598.namprd08.prod.outlook.com><br>
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Content-Type: text/plain; charset="windows-1252"<br>
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Hello,<br>
<br>
While reviewing AMS software suite for installation, I noticed this remark (<a href="https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system">https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system</a>):<br>
<br>
-----<br>
<br>
GPFS file system<<a href="https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system">https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system</a>><br>
<br>
Starting with AMS2019, the KF sub-system (used for handling binary files such as ADF?s TAPE* files) has been rewritten to use memory-mapped files. The mmap() system call implementation is file-system dependent and, unfortunately, it is not equally efficient
in different file systems. The memory-mapped files implementation in GPFS is extremely inefficient. Therefore the users should avoid using a GPFS for scratch files<br>
<br>
--------<br>
<br>
Is this claim true? Are there caveats to this statement, if true?<br>
<br>
<br>
Thanks,<br>
<br>
<br>
Oluwasijibomi (Siji) Saula<br>
<br>
HPC Systems Administrator / Information Technology<br>
<br>
<br>
<br>
Research 2 Building 220B / Fargo ND 58108-6050<br>
<br>
p: 701.231.7749 / www.ndsu.edu<<a href="http://www.ndsu.edu/">http://www.ndsu.edu/</a>><br>
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Message: 2<br>
Date: Tue, 22 Jun 2021 15:55:54 +0000<br>
From: Simon Thompson <S.J.Thompson@bham.ac.uk><br>
To: gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
Subject: Re: [gpfsug-discuss] GPFS bad at memory-mapped files?<br>
Message-ID: <14CCBDE7-AB03-456B-806B-6AD1A8270A7D@bham.ac.uk><br>
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There certainly *were* issues.<br>
<br>
See for example: <a href="http://files.gpfsug.org/presentations/2018/London/6_GPFSUG_EBI.pdf">
http://files.gpfsug.org/presentations/2018/London/6_GPFSUG_EBI.pdf</a><br>
And the follow on IBM talk on the same day: <a href="http://files.gpfsug.org/presentations/2018/London/6_MMAP_V2.pdf">
http://files.gpfsug.org/presentations/2018/London/6_MMAP_V2.pdf</a><br>
<br>
And also from this year: <a href="https://www.spectrumscaleug.org/event/ssugdigital-spectrum-scale-expert-talks-update-on-performance-enhancements-in-spectrum-scale/">
https://www.spectrumscaleug.org/event/ssugdigital-spectrum-scale-expert-talks-update-on-performance-enhancements-in-spectrum-scale/</a><br>
<br>
So it may have been true. If it still is, maybe, but it will depend on your GPFS code.<br>
<br>
Simon<br>
<br>
From: <gpfsug-discuss-bounces@spectrumscale.org> on behalf of "Saula, Oluwasijibomi" <oluwasijibomi.saula@ndsu.edu><br>
Reply to: "gpfsug-discuss@spectrumscale.org" <gpfsug-discuss@spectrumscale.org><br>
Date: Tuesday, 22 June 2021 at 16:17<br>
To: "gpfsug-discuss@spectrumscale.org" <gpfsug-discuss@spectrumscale.org><br>
Subject: [gpfsug-discuss] GPFS bad at memory-mapped files?<br>
<br>
Hello,<br>
<br>
While reviewing AMS software suite for installation, I noticed this remark (<a href="https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system">https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system</a>):<br>
<br>
-----<br>
<br>
GPFS file system<br>
<br>
Starting with AMS2019, the KF sub-system (used for handling binary files such as ADF?s TAPE* files) has been rewritten to use memory-mapped files. The mmap() system call implementation is file-system dependent and, unfortunately, it is not equally efficient
in different file systems. The memory-mapped files implementation in GPFS is extremely inefficient. Therefore the users should avoid using a GPFS for scratch files<br>
--------<br>
<br>
Is this claim true? Are there caveats to this statement, if true?<br>
<br>
Thanks,<br>
<br>
<br>
Oluwasijibomi (Siji) Saula<br>
<br>
HPC Systems Administrator / Information Technology<br>
<br>
<br>
<br>
Research 2 Building 220B / Fargo ND 58108-6050<br>
<br>
p: 701.231.7749 / www.ndsu.edu<<a href="http://www.ndsu.edu/">http://www.ndsu.edu/</a>><br>
<br>
<br>
<br>
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