Re: io_u error using offsets

[Jens Axboe <axboe@kernel.dk>]

On 2012-11-19 18:46, Georg Schönberger wrote:
> Hello,
> 
> I am trying to divide a 4TB hard disk into 128 equal parts. Therefore I divide the disk size (in Bytes) with 128 - this is my increment size. Then I start several fio job rounds with the offset increasing every round by the increment. Unfortunately I get an error for the first offset not equal to 0.
> I suppose this is an issue with the offsets not being correctly aligned.
> Here is my call to fio:
> $ sudo /usr/local/bin/fio --rw=randrw --name=wd --offset=31256148672 --direct=1 --bs=64k --filename=/dev/sdi --rwmixread=100 --numjobs=1 --ioengine=libaio --runtime=60 --iodepth=16 --size=31256148672 --group_reporting --debug=all

You get the error because 31256148672 isn't a multiple of 512b (which
I'm assuming is your sector size), hence the IO will be unaligned.
Direct IO cannot be unaligned, that's why you get an EINVAL from the OS.

-- 
Jens Axboe