On Fri, Aug 09, 2013 at 03:06:37PM +0200, Yan, Zheng wrote: > On Fri, Aug 9, 2013 at 5:03 PM, 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' ? > > you can get/set file layout through virtual xattr. for example: > > # getfattr -d -m - targetfile > > > (2) how to use those parameters to achieve different optimized layouts on CephFS directories > > (e.g. for streaming, small sequential IOs, small random IOs) > > > > ceph directories are not implemented as files. you can't optimize ceph > directories by this way. In my view 'Directories' in CephFS are similar to 'Volumes' in RBD. With 'rbd create --order 16 new-volume' I can assign an object size to a volume. With 'cephfs directory set_layout ...' I can set similar parameters to a directory: # mkdir /mnt/cephfs/test-dir # cephfs /mnt/cephfs/test-dir show_layout layout not specified # cephfs /mnt/cephfs/test-dir set_layout -p 3 -s 4194304 -u 4194304 -c 1 # cephfs /mnt/cephfs/test-dir show_layout layout.data_pool: 3 layout.object_size: 4194304 layout.stripe_unit: 4194304 layout.stripe_count: 1 # echo asd > /mnt/cephfs/test-dir/test-file # cephfs /mnt/cephfs/test-dir/test-file show_layout layout.data_pool: 3 layout.object_size: 4194304 layout.stripe_unit: 4194304 layout.stripe_count: 1 The set_layout attribute of a DIR will be inherit to the FILES below. My question is: which combination of "--stripe_unit --stripe_count --object_size" will be optimal for streaming, small sequential IOs, small random IOs ? (in/below a DIR) Best Regards, -Dieter > > Regards > Yan, Zheng > > > -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
