Fam - Distributed file system

Hi all

I have an term project for a new distributed file system.My problem is
about fam.I give an example for it.

if some system user changed any file which has a high capacity like 100
mb.I must copy this file to the other mirrors from the network because
fam's software "fileschanged" don t give the changed block number of
file.It only reports the file name like "/home/user/file.txt is
changed". so i can not transfer the altered blocks to the other
mirrors.
I know "This is an optimization problem" if anybody solved it before,
can he give me any suggestion ?

thanks

.