If you must use rsync copying data from oldHostname to newHostname, you can use rsync's exclude directive.
For example, you many want to exclude the /opt/zimbra/data/ldap/mdb/db/data.mdb file.
rsync -av --exclude '*.mdb*' /opt/zimbra root@newHostname:/opt/zimbra
Rsync may see the data.mdb's file size as a sparse file, that is created to be the same size as the DB maxsize. i.e., there will be a data.mdb file on disk that appears to be 80GB in size. See, https://wiki.zimbra.com/wiki/OpenLDAP_Performance_Tuning_8.0#Notes_on_MDB
You may also want to exclude the mysql's ib_logfiles too, as these tend to be large as well.
rsync -av --exclude '*.mdb*' --exclude '*ib_logfile*' --exclude 'ibdata1' /opt/zimbra root@newHostname:/opt/zimbra
More articles written by me, https://wiki.zimbra.com/wiki/King0770-Notes