Welcome to the forums
Well, is the new server the same O/S and version of ZCS ? If so then why not just follow
Wiki :: FOSS Recovery. Of course it would help if you were to let us know which version of ZCS you were running
Code:
su - zimbra
zmcontrol -v
Are you sure it is the data store that is full under /opt ? Perhaps you could also post the following
Code:
cd /opt/zimbra
du -k .