Hi, Object map feature was added in hammer. It is possible to create and delete an image with object map enabled using rbd, though it is not possible to map the image which has object map or exclusive lock features enabled, e.g.: ceph@ceph1:~$ rbd create foo --size=42 --image-format=2 --image-features=15 ceph@ceph1:~$ sudo rbd map foo rbd: sysfs write failed rbd: map failed: (6) No such device or address I checked rbd.c in linux/drivers/block/rbd.c, it looks like that it only supports layering and striping as of kernel 4.1 branch. #define RBD_FEATURE_LAYERING (1<<0) #define RBD_FEATURE_STRIPINGV2 (1<<1) #define RBD_FEATURES_ALL \ (RBD_FEATURE_LAYERING | RBD_FEATURE_STRIPINGV2) /* Features supported by this (client software) implementation. */ #define RBD_FEATURES_SUPPORTED (RBD_FEATURES_ALL) Is object map a partial feature in hammer? If so, will there be a complete support of object map in some upcoming ceph release? -- 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