Lines 17 and 18 in conf.php :
Code:
$fm['archive']['compress'][0] = range(0, 0);
$fm['archive']['compress'][1] = array('-0');
For store compression (rar and zip).
Check the indexes in this array:
Code:
$fm['archive']['types'] = array('rar', 'zip', 'tar', 'gzip', 'bzip');