Difficult folder merge - need ideas

OK guys, I have 2 Hard drives, both drives contain the same folders but with different files in each folder.

What I need to do is combine the contents of both drives somehow without physically merging the files on those drives so that they can be backed up to a single location on one of my NAS.

I use Beyond Compare to do my backups but when I attempt to do what I want, the folder sync operation wants to delete the files from one drive or the other, depending on which drive is selected at the time. I can set up file ignore rules, but there is just too damn many files to deal with. I have similar issues with other backup software also.

EG:

Drive D: ------> Single Folder On NAS 2
Drive E: -^

Drive D: ------> NAS 1

The files on Drive D: are uploaded to two different NAS's one of which is full. So no files can be added to D: and therefore any additional files are added to Drive E:. The files on Drive E: are uploaded to only one NAS which has room to spare.

Anyone have any suggestions?

As I understand the question, I just create 2 Folders on my NAS, open a second copy of Windows Explorer, set them side by side, go the Folder to be copied and drag it to the first WE window. One of the reasons I do it that way is that it's much faster later to move files from one Folder to another Folder on the same drive as desired and the other is to run a duplicate checking program on them which seems to be always faster than checking one HDD against another. I do have to be careful with the drag and drop that I get the right target.

Yeah that could work, but I need to keep an eye on what is copied and what is not and to where, so that I know when I need to update the backup and so on.

Dealing with TB's of files can take a lot of time copying from one place to another even if they are located on the same physical drive which is one of the reasons I'm looking for a better solution ... lol

Renaming the files is not an option?

You may want to give Acronis a shot.

@Callender, Teracopy doesn't work the way I need it to at all. If memory serves it is similar to beyond compare as far as file syncing goes.

@Doctore, No, renaming the files is not an option.

Yeah I have tried Acronis and quite a few others, they all suffer from the same issue. If you are 'syncing' files from one drive and there are files from the other drive present, they want to delete the files that are already there.

You see the biggest problem with all of these programs is that they only copy from A to B.

I need something that copies from A & B to C.

Thanks for the replies so far though guys, there are some good suggestions among them.

I found a small program called FolderMerge on SourceForge and it does half of what I need, that is, it will copy from A & B to C but there is no way to compare C with A & B to make sure everything is up to date and no duplicates etc.