cephfs set_layout - EINVAL

[Kasper Dieter <dieter.kasper@ts.fujitsu.com>]

Hi,

my goal is to set the 'object size' used in the distribution inside rados
in an equal (or similar) way between RBD and CephFS.

To set obj_size=64k in RBD I use the command:
rbd create --size 1024000 --pool SSD-r2 ssd2-1T-64k --order 16  

On cephfs set_layout '-s 65536' runs into EINVAL:
cephfs /mnt/cephfs/fio-64k/ set_layout -p 3 -s   65536 -u 4194304 -c 1
Error setting layout: Invalid argument

cephfs /mnt/cephfs/fio-64k/ set_layout -p 3 -s   65536 -u 65536 -c 1
cephfs /mnt/cephfs/fio-64k/ show_layout
layout.data_pool:     3
layout.object_size:   65536
layout.stripe_unit:   65536
layout.stripe_count:  1

The man page of cephfs says
---snip---
       -u --stripe_unit
              Set the size of each stripe

       -c --stripe_count
              Set the number of objects to stripe across

       -s --object_size
              Set the size of the objects to stripe across
---snip---

What is the equivalent command on cephfs to 'rbd create --order 16' ?
Can you please give same explanation how "--stripe_unit --stripe_count --object_size"
should be used in combination to achieve different layouts on CephFS directories
(e.g. optimized for streaming, small sequential IOs, small random IOs)
?

Thanks,
-Dieter