Re: Using fio with adjusted parameters for use case "DB"

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Hello,

thanks for your reply.

I have discussed with DB developers which values should be used for
- iodepth and
- numjobs

With regards to iodepth I was told that a max. value could be defined in DB's global ini; the default is 512. This means the DB could use this queue depth as max. but certainly no as average.

Question:
From your experience, does it make sense to run IO benchmark with iodepth=512?


THX



Am 07.03.2023 um 16:22 schrieb Vincent Fu:
On 3/7/23 09:30, Thomas Schneider wrote:
Hello,

I want to benchmark different storage devices with an I/O workload generated by the "real" application: DB.

A typcial command could be:
fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=1024 --direct=1 --size=64m --numjobs=2 runtime=120s

The question is regarding parameters size and runtime:
- What value should be used for size? Should this be the same as allocated disk space by DB data files? Or just a (reasonable) portion of this? DB data files could be up to xTB. - Is it advisable to use runtime? If yes, would this somehow contradict to size, means if I use a larger size, then runtime is obviously longer.


The documentation for runtime is here:

https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-runtime

Fio will write within the LBAs bounded by offset and size and stop when it has touched all the LBAs or when runtime is attained. Run some experiments with --debug=io to better understand fio's behavior.

Also take a look at the example job files for help:

https://github.com/axboe/fio/tree/master/examples

Vincent





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