Reported by Bastien Jaillot, Feb 22, 2010
because it takes loooooooooooong time to generate when you don't use SSD :).
Comment 1 by Loïc d'Anterroches, Feb 22, 2010
Comment 2 by Loïc d'Anterroches, May 19, 2010
Fixed in commit ad6148c. Put: $cfg['idf_no_size_check'] = true; and it will not check the size.
Comment 3 by Thomas Keller, Nov 25, 2010