This object gives the size of the partition in megabytes, calculated using 1,048,576 bytes per megabyte, which may differ from a drive manufacturer's advertised capacity. An admin planning to carve a new LUN from this partition would check this size to confirm it provides enough capacity for the intended volume. For example, comparing this value against the parent device's total size shows an admin how much of the underlying disk or storageset remains unpartitioned.