fio laying out file question

fio laying out file question

[Yuyang Wang]

hi all

I am using fio (2.1.7) for a simple sequential write test (see command
below). It seems the process will get stuck on "Laying out IO file" for a
long long time ...  Of course, smaller size take less time for layout,  I
am curious as to, is FIO trying to precreate the file before doing write,
what's going on there?

./fio --rw=write --size=128g --bs=8m --filename=/test/$RANDOM
--ioengine=posixaio --iodepth=16 --name=mytest

Thanks

Alex

Re: fio laying out file question

[Jens Axboe]

On 04/16/2014 08:21 AM, Yuyang Wang wrote:
> hi all
> 
> I am using fio (2.1.7) for a simple sequential write test (see command
> below). It seems the process will get stuck on "Laying out IO file" for a
> long long time ...  Of course, smaller size take less time for layout,  I
> am curious as to, is FIO trying to precreate the file before doing write,
> what's going on there?
> 
> ./fio --rw=write --size=128g --bs=8m --filename=/test/$RANDOM
> --ioengine=posixaio --iodepth=16 --name=mytest

For a pure write, it wont layout the file completely first. I'm guessing
you are stuck in fallocate - depending on the file system, that will
fill out blocks. You can try and add fallocate=none, that should get rid
of it.

-- 
Jens Axboe