We've been migrating about 220 GB of data from a Windows 2003 Server to a Windows 2008 Server, and because of the time it would take to copy that data and the necessity of keeping it available for users, I came up with the idea of using rsync on an Ubuntu server to broker the migration. (I might have gone for a proper Windows solution - but the applications I found were a bit pricey for a one-shot like this - and permissions are not a problem).

All well and good - and today I'm making the last sync and confirming that the new server is up-to-date using diff, but I"ve noticed an odd thing with Excel spreadsheets (.xls).

Every instance of an Excel spreadsheet that has already been copied in a previous in a previous synchronisation is being marked as "already up-to-date" by rsync. However, when I then run a diff, I'm told that the files differ. I'm manually copying them, as there are but a handful, but I was wondering what might be causing this.

No other filetype in the entire 220 GB tree has had any problem like this - just the Excel/xls files. It'd be great if someone could come up with an explanation.