Synch group with different gid

[Fabian Cenedese]

Hello

I have a problem while synching between two NAS boxes with Linux.
First NAS: group staff=50 (3.0.3pre1)
Second NAS: groups ftp=50, staff=500 (rsync 3.1.1)

I synched with -rptgo, without --numeric-ids. The expected result
was that the items on the second group would be staff as well
even with a different gid. However it looks like the 50 was taken
literally and now all staff items are ftp items.

1. How could this happen? Is this expected, did I do something wrong?
2. How can I now synch the ownership correctly?

I tried with -a, with --super, but so far the ownership is not synched.

Thanks

bye  Fabi