First disclaimer... I'me really a network novice.

I've used XXCOPY and Robocopy to successfully back up entire volumes
to an eSATA connected drive, but when I try to do the same to a newly
acquired NAS drive, it doesn't work right. Instead of copying "only"
the files that are new (or changed since the last backup), Robocopy
copies every file over again.

And XXCOPY (free version) won't copy at all to the NAS drive. I
downloaded the 60day trial of XXCOPY home, and it does work right,
(except it recopies lots of zipped files) but XXCOPY home costs $40.

Here's a typical command (from a batch file) for each:

Robocopy E: \\DLINK\Volume_1\E-BACKUP /MIR /R:1 /W:1

and

xxcopy e:\ \\dlink\volume_1\e-backup /clone/ff

I also found RichCopy, which I tried, and find it also copies files
that are already in place on the NAS drive.

Could it be that I have a problem with the way I've set up the NAS?

I'm probably overlooking something basic, and if so would really
appreciate some advice.

Everything is what it is because it got that way....D'Arcy Thompson