Re: IOPS higher than expected on randwrite, direct=1 tests

[Sebastian Kayser <sebastian@xxxxxxxxxx>]

* Jens Axboe <jaxboe@xxxxxxxxxxxx> wrote:
> On 2010-11-10 20:52, Sebastian Kayser wrote:
> > * John Cagle <jcagle@xxxxxxxxx> wrote:
> >> If the disk is 2TB, then your 100GB test is only using 5% of it-- thus
> >> your observed IOPS will be a lot better than expected due to
> >> short-stroking.  Right?
> > 
> > I don't know. The inital 80 IOPS (observed over about 2 full minutes)
> > made me believe that 100GB would have covered a high enough percentage
> > to at least eliminate track-to-track seeks. Are short-stroked seeks also
> > that much faster compared to average seek times? And where would the
> > steady increase in IOPS during the test come from?
> > 
> > But you are definitly right when it comes to the test setup. I just
> > started a test with size=1800g. Looking foward to what that will show.
> 
> If you have the full device, you could just test on that instead of
> using a filesystem and file. Just to get more 'raw' performance.

Thanks. This also turned out to be much more feasible for "quick" test
turn-around. As soon as I ran the tests with size=1800g it took ages to
prepare the test file (~30 MB/s towards the iSCSI target) and one disk
even quit on me over night.

When staying within the realm of file based testing, can fio determine
and display the progress (think: progress bar or percentage) when it
prepares the test file?

Sebastian
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