[gpfsug-discuss] GPFS bad at memory-mapped files?

Simon Thompson S.J.Thompson at bham.ac.uk
Tue Jun 22 16:55:54 BST 2021

There certainly *were* issues.

See for example: http://files.gpfsug.org/presentations/2018/London/6_GPFSUG_EBI.pdf
And the follow on IBM talk on the same day: http://files.gpfsug.org/presentations/2018/London/6_MMAP_V2.pdf

And also from this year: https://www.spectrumscaleug.org/event/ssugdigital-spectrum-scale-expert-talks-update-on-performance-enhancements-in-spectrum-scale/

So it may have been true. If it still is, maybe, but it will depend on your GPFS code.


From: <gpfsug-discuss-bounces at spectrumscale.org> on behalf of "Saula, Oluwasijibomi" <oluwasijibomi.saula at ndsu.edu>
Reply to: "gpfsug-discuss at spectrumscale.org" <gpfsug-discuss at spectrumscale.org>
Date: Tuesday, 22 June 2021 at 16:17
To: "gpfsug-discuss at spectrumscale.org" <gpfsug-discuss at spectrumscale.org>
Subject: [gpfsug-discuss] GPFS bad at memory-mapped files?


While reviewing AMS software suite for installation, I noticed this remark (https://www.scm.com/doc/Installation/Additional_Information_and_Known_Issues.html#gpfs-file-system):


GPFS file system

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

Is this claim true? Are there caveats to this statement, if true?


Oluwasijibomi (Siji) Saula

HPC Systems Administrator  /  Information Technology

Research 2 Building 220B / Fargo ND 58108-6050

p: 701.231.7749 / www.ndsu.edu<http://www.ndsu.edu/>

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