Backup job copies ALL files instead only changes

The backup is actually done by Acronis vmProtect. Each backup is done to a separate file, and to my knowledge the old files do not change. Thus, all I need is to copy the non-existent files. This should be the easiest incremental backup possible...and yet it copies EVERYTHING. Ugh!

I have looked at rsync using 127.0.0.1 as the "remote" server. However, I'm skeptical that rsync can do better. I know rsync is supposed be faster because it copies only the changed portions of files, but how does it determine what's changed? Seems to me there's only two possible ways.

1. Does it do a timestamp and size comparison and skip ones that are the same? That would be nice if it worked, but since the current backup can't accomplish that--possibly because of the problems with different filesystems that you mention--why would rsync perform any better?


2. Or does it read both the source and destination files, perform some sort of checksum, and then copy only the pieces that changed? I can see that being quite efficient with a client/server over a low-bandwidth connection with mostly static data. However, within the same box that takes almost as long as flatout copying everything because everything in both the source and destination will need to be read once, checksum calculated, plus a possible write to the destination. In fact, worst case it could actually take longer if all files changed.

Also, with rsync I have another failure point: username and password. With Share > USB, I don't have to worry about disabled accounts or changed passwords.

However, I can't continue as is, so unless someone can offer a fix, I guess I'll have to try rsync after the current job gets done copying everything again.