Hello, Ops, you wrote: I eat>> And it is able to double changes in the big files without rescanning/comparison? Ops> and how it to make, let theoretically? So that it was more effective than comparing. What for theoretically - MirrorFolder it does practically, installing driver-filter FS for tracing of modifications in initial trees. I it now test - it absolutely fairly changes at level of sectors. That is, if in a file to re-record one sector - it is instantly re-recorded and in a mirror file. Accordingly, it is correct in real time containers of the virtual disks opened in not divided modes, to read which of user-mode process at the mounted disk it is impossible. As far as I understand, in it MirrorFolder it is unique, I did not find other such product. If at testing does not get out glitches - I will buy. One is bad - at it templates of eliminated subdirectories are applied, seemingly, only to already selected names of subdirectories, instead of to a way as a whole. That is, to eliminate studio target subdirectories, type "debug\win32", "release\x64", it does not turn out, and to eliminate separately debug, release, win32, x64 - not a variant for I have such subdirectories with the useful files. That is, to specify one root process directory, eliminating in it similar subdirectories with temporal/derivative files, does not quit, and to fence the difficult description of a tree from several tens products - boringly and unreliably.