+
+ def optimize_image(self, rootdir):
+ """
+ Filing up the image with zeros will increase its compression rate
+ """
+ zeros = os.path.join(rootdir, 'ZEROS')
+ self.runcmd_unchecked(['dd', 'if=/dev/zero', 'of=' + zeros, 'bs=1M'])
+ self.runcmd(['rm', '-f', zeros])
+
+