Yep, I too have a problem with my brand new Terastation 3 TS-XL 4TB (firm V1.40) :-( and i'm proper annoyed about it as like many other posters here i bought the box with the intention of using xcopy to automate backups.
At first I thought it was me being daft but i am reassured that others are experiencing the same problem - I tried xcopy with /s /e /d /c /h /r /y, using uppers and lowers also tried using windows synctoy and that was just as confused by the filestamp issue.
I personally feel the whole firmware feels pretty cheap and flaky and i am deeply disappointed - for not much more i could have bought a basic dell/hp server with a proper cpu and/or put my own drives in it with either win server or freenas on it and i'm already wishing (as is so often the case with these things) that i'd read this forum BEFORE shelling the £600 for the drive..
Well thats the bad news, the good news for the rest of the folks here is that I am a windows developer 'by trade' and i have already started work on an app to replace the functionality of xcopy but make allowances for these differences in filestamp and/or use other criteria for determining if the files have changed (thinking either a dat file like synctoy uses or a combination of archive bit setting/size analysis).
i know there are other apps out there but I'm writing this from scratch just for the purpose as I reckon the code monkeys at buffalo are unlikely to invest any effort into fixing this and i need to get this working quicker than they ever will - i should be able to get this running over the next few days and i will release it for no charge when its ready.
Incidentally a quick fix is to use a container based backup solution. Windows Backup and Backup Exec are both happy locating the BackupToDisk location on the drive and they will be unaffected by this issue as they retain there own filestamp info inside that backup media although this doesnt really solve the problem if you use the drive as a destination in 'normal' file transactions.
I wonder if that is why buffalo are now offering noveo backup (or whatever it is called) free if purchased after a certain date.
I will post again with results or updates as soon as i can.