rsync on os x

[giacomo.ulivieri at unifi.it]

hi,
i've some problem with rsync on my os x 10.4.
the rsync was periodically launched by an applescript
i backup data from many machines (6) to an IP big volume (Lacie 1.8
TBytes)
after some day of fine work, i found no syncronization on my Lacie.
from apple window i mount a DATA volume on my desktop and i don't find
that the sync was 
stopped at two days afore
however from terminal cd /Volumes/ i found two different destination
directory:
DATA and DATA-1, where the second one (not created by anyone) contain
the not sync 
folders, subfolders and files relative to the all client machines while
the first one contain only 
1 folder relative to one machine with synced folders, subfolders and
file.

i don't understand what's happen and why the DATA-1 folder was created.

have you some advice?

thank you 1000