> > OSD bench performs IOs at the objectstore level and the stats are
> > reported
> > based on the response from those transactions. It performs either
> > sequential
> > or random IOs (i.e. a random offset into an object) based on the
> > arguments
> > passed to it. IIRC if number of objects and object size is provided, a
> > random
> > offset into an object is written.
> > 
> > Therefore, depending on the parameters passed, sequential or random
> > offset
> > is determined and this obviously would result in different measurements.
> 
> 
> Do you know if it tries and do this on times where the osd is not being 
> actively used or waits until there is no activity? I have been testing a bit 
> recently and noticed that some ssd's of the same type are reporting 
> significantly different values like 117 and 90


I am doing this test on a lab cluster, freshly installed, with no activity and 
almost no data on it. So disks should be standby in-between tests.

And I performed various runs, and even if the results are note exactly the 
same, they are in the same order of magnitude (1% or 2% difference between 
runs), and the differences between disk vendor are quite high, and consistent 
between runs.
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