-r, --resize

rather than format the disk, it can be resized. This means changing the number of blocks on the device reported by the READ CAPACITY command. This option should be used with the --count=COUNT option. The contents of all logical blocks on the media remain unchanged when this option is used. This means that any resize operation can be reversed.

-c, --count=COUNT

where COUNT is the number of blocks to be formatted or media to be resized to. Can be used with either --format or --resize.

(COUNT = -1) : after resize READ CAPACITY will report its maximum number of blocks