Your first exabyte in a Ceph cluster

$ rbd create --size $((1024 * 1024 * 1024 * 1024)) tiny
$ rbd info tiny
rbd image 'tiny':
	size 1024 PB in 274877906944 objects
	order 22 (4096 kB objects)
	block_name_prefix: rb.0.1009.6b8b4567
	format: 1

Note: rbd rm tiny will take a long time.