xfs over linux raid5 perffered blocksize

["Raz Ben-Jehuda(caro)" <raziebe@xxxxxxxxx>]

Hello

I need to create a writer which creates files over linux software raid5.
the files must be aligned by the stripe unit and so as the extents.

If an extent SIZE is not a factor of the stripe unit it is as if i have
done nothing.

I have learned by reading the documentatiom that the preffered io size
is the stripe width. that seems to work. I am reserving space and writing
3MB size buffers to raid5 with 1MB stripe unit over 4 disks.

my question:
Can I rely on it ?
Can I enforce this behaviour ?

thank you
--
Raz