fio: first direct IO errored

[Christian Zoffoli <czoffoli@xmerlin.org>]

Hi to all,
I'm testing a storage (14x300GB) with different RAID levels, volume
stripe sizes and different blocksizes and numjobs in fio ...but I've
found a problem testing it with disks in RAID6 configuration.

here is the command line I've used

-----
fio --filename=/dev/dm-0  --direct=1 --group_reporting  --rw=read
--bs=1k --numjobs=1 --runtime=60  --name="read-bs512-job1"
-----

and here is the error:

-----
read-bs512-job1: (g=0): rw=read, bs=1K-1K/1K-1K, ioengine=sync, iodepth=1
Starting 1 process
fio: first direct IO errored. File system may not support direct IO, or
iomem_align= is bad.
fio: pid=4898, err=22/file:engines/sync.c:62, func=xfer, error=Invalid
argument

read-bs512-job1: (groupid=0, jobs=1): err=22 (file:engines/sync.c:62,
func=xfer, error=Invalid argument): pid=4898
  cpu          : usr=0.00%, sys=0.00%, ctx=0, majf=0, minf=50
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%,
>=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%,
>=64=0.0%
     complete  : 0=50.0%, 4=50.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%,
>=64=0.0%
     issued r/w/d: total=1/0/0, short=0/0/0



Run status group 0 (all jobs):

Disk stats (read/write):
  dm-0: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=-nan%,
aggrios=0/0, aggrmerge=0/0, aggrticks=0/0, aggrin_queue=0, aggrutil=0.00%
    sdb: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
    sdd: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
    sdc: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
    sde: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00

-----


testing the same volume with RAID10 works as expected.

Is it related to the size of the volume?
In RAID6 is 3.3TB and 2.1TB in RAID10.

I've tried also with --norandommap but without success.

and I've not understood what I have to put in iomem_align= to fix the
"alignment" problem.


Best regards,
Christian
-- 
Christian Zoffoli (XMerlin)

You never change things by fighting the existing reality. To change
something, build a new model that makes the existing model obsolete."
-- R. Buckminster Fuller