[lustre-discuss] strange time of reading for large file

[Rosana Guimaraes Ribeiro]

Hi,


I have some doubts about Lustre, I already sent my issues to forums but no one answer me.

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.
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:

Write time [sec]:
325.77
318.80
325.44
458.54
316.89
327.75
344.90
340.34
383.57
316.35

Read time [sec]:
570.48
601.11
447.14
406.39
480.44
5824.40
299.40
293.54
1049.93
4190.47

We ran on the single client with 1 process and tested on same infrastructure (hardware and network).
Could you explain why is reading time so distorted? What kind of problem might be occurring?


Regards,

Rosana

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