'The DotHill creates a snap pool before trying to copy the volume.
The pool is 5.27GB or 20% of the volume size, whichever is larger.
Verify that we have enough space for the pool and then copy'

def _assert_enough_space_for_copy(self, volume_size):

    pool_size = max((volume_size * 0.2), 5.27)
    required_size = (pool_size + volume_size)
    if (required_size > self.stats['pools'][0]['free_capacity_gb']):
        raise exception.DotHillNotEnoughSpace(backend=self.backend_name)
