On Fri, Aug 9, 2013 at 2:03 AM, Kasper Dieter <dieter.kasper@xxxxxxxxxxxxxx> wrote: > OK, > I found this nice page: http://ceph.com/docs/next/dev/file-striping/ > which explains "--stripe_unit --stripe_count --object_size" > > But still I'm not sure about > (1) what is the equivalent command on cephfs to 'rbd create --order 16' ? There's not a direct one; CephFS lets you specify arbitrary sizes (--stripe-unit) while rbd restricts you to powers of two. If you want a new file to use a 64KB object size you can just set the object_size to be 64KB. > (2) how to use those parameters to achieve different optimized layouts on CephFS directories > (e.g. for streaming, small sequential IOs, small random IOs) If (as Yan suspects) you mean specifying how the directory is laid out on disk, you can't — CephFS directories aren't maintained that way and it wouldn't make any sense. If you're talking about making all the files underneath it use a new layout, you can specify a directory layout which is applied to all new descendent files the same way as you specify the layout on an individual file. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com > > -Dieter > > On Fri, Aug 09, 2013 at 09:44:57AM +0200, Kasper Dieter wrote: >> 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 > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
