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.