Ceph » rbd

The current way of creating RBD format 2 images is calling either rbd_create2 or rbd_create3.

Older binaries like qemu-img, qemu, libvirtd, etc all call rbd_create and thus still create RBD images with format 1.

Josh suggested that we might change the default behavior of librbd: http://thread.gmane.org/gmane.comp.file-systems.ceph.devel/15048/focus=15064

Adding these configuration options:

rbd_create_default_format UINT default 1

or we could add other options to adjust the rest of the image creation
parameters i.e.:

rbd_create_default_object_order INT default 22

rbd_create_default_features UINT64 default 1 # 1 for layering, 3 for layering+stripingv2

rbd_create_default_stripe_count UINT64 default 1 # changing requires stripingv2 feature

rbd_create_default_stripe_unit UINT64 default 4194304 # changing to non-object size requires stripingv2 feature

This is somewhat related to: #4897