On Wed, Aug 14, 2013 at 10:17:24PM +0200, Gregory Farnum wrote: > 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. Thank you Greg, my question was which parameters of "--stripe_unit --stripe_count --object_size" would be optimal for new descendent files under directories /mnt/cephfs/streaming /mnt/cephfs/seq-IOs /mnt/cephfs/rand-IOs e.g. cephfs /mnt/cephfs/streaming set_layout -p 3 -s 4194304 -u 4194304 -c 1 cephfs /mnt/cephfs/seq-IOs set_layout -p 3 -s 4194304 -u 65536 -c 8 cephfs /mnt/cephfs/rand-IOs set_layout -p 3 -s 65536 -u 65536 -c 1 -Dieter > -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
