Re: multiple block devices question

[David Nellans <david@nellans.org>]

On 07/03/2014 12:28 PM, Yuyang (Alex) Wang wrote:
> Carl,
>
> Specifying them as separate jobs will do what I expect. However, in
> this case, I am seeking to know how much performance and how many
> devices can a __single__ FIO process can drive. If my above
> configuration is correct, then, for some reason, the single process
> doesn't increase with more devices at its disposal, not as I have seen
> from another benchmark tool - which is puzzling. I am curious to
> understand why.
>
> Best,
>
> A.
If you want to benchmark fio throughput or the block layer, not your 
actual raid array,
then use a ramdisk.  There are lots of flash devices out there now which 
will push far
more than 1.4GB/s from a single device,  rest assured fio isn't your 
limitation here.
1.4 GB/s with 1M block sizes isn't even 2k IOPS.  fio pushes 500k IOPS 
through the block layer
without issue, its not your limiting factor.