Simulating bursts at different rates at irregular intervals?

[James Vanns <james.vanns@framestore.com>]

Hi. I'm new to fio and though I've read the HOWTO from the git repo several times now, I'm unsure if it is possible to achieve what I want;

I can simulate a mix of sequential and random writes for a duration at an average rate or throughput of say, 5.4MB/s.
I presume that fio will attempt to sustain that rate? My real question is this - is it possible in either the same job
or a different job in the same file to simulate bursts of higher rates? I.e. on average attempt to write at nMB/s but
at random or irregular intervals during this period attempt a 'burst' of 138MB/s for 5 minutes and then return to the 'normal' rate. Then again at some other point a burst of 57MB/s for 30minutes etc.

Is this possible? Presently I've found that I cannot do this. Or rather, thinking about it, I'd have to specify n jobs 
for each different rate and then perhaps use 'ratecycle' and 'thinktime'? I can't see how to skew 'thinktime' randomly though?

Regards,

Jim Vanns

-- 
Jim Vanns
Senior Software Developer
Framestore