FIO cheat sheet

With any luck I’ll turn this into a real blog post soon, but for the moment: a cheat sheet for simple usage of fio to benchmark storage. This command will run 16 simultaneous 4k random writers in sync mode. It’s a big enough config to push through the ZIL on most zpools and actually do some testing of the real hardware underneath the cache.

fio --name=random-writers --ioengine=sync --iodepth=4 --rw=randwrite --bs=4k --direct=0 --size=256m --numjobs=16

For reference, a Sanoid Standard host with two 1TB solid state pro mirror vdevs gets 429MB/sec throughput with 16 4k random writers in sync mode:

Run status group 0 (all jobs):
  WRITE: io=4096.0MB, aggrb=426293KB/s, minb=26643KB/s, maxb=28886KB/s, mint=9075msec, maxt=9839msec

Awww, yeah.

378MB/sec for a single 4k random writer, so don’t think you have to have a ridiculous queue depth to see outstanding throughput, either:

Run status group 0 (all jobs):
  WRITE: io=4096.0MB, aggrb=378444KB/s, minb=378444KB/s, maxb=378444KB/s, mint=11083msec, maxt=11083msec

That’s a spicy meatball.

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Jim Salter

Mercenary sysadmin, open source advocate, and frotzer of the jim-jam.

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