When copying files there are two costs - fixed per-file cost (of opening/closing a file) and variable cost of bulk copying. If you track both, you can pass the

When copying files there are two costs - fixed per-file cost (of opening/closing a file) and variable cost of bulk copying. If you track both, you can pass the measurements through basic linear regression and get a simple formula - ETA = A * number-of-file + B * number-of-bytes This can be further refined to accomodate the cost of file extension for larger file, the overhead of directory creation, etc, but in practice basic two-term model works really well. There was an earlier post on HN on this, let me see if I can find it ... edit ... Nope, not HN. I was thinking of this - http://www.bvckup.com/support/forums/topic_show.pl?tid=101 http://www.bvckup.com/support/forums/topic_show.pl?tid=101