In a previous thread on this forum, it states "iSCSI Volume Replication is synchronous and NAS Data Replication is synchronous and asynchronous. Block IO for iSCSI/NAS in latest version."
Perhaps I haven't understood exactly what's meant by this; I've create a NFS Share on two open-e DSS boxes (lets call it "test").
I've set box 1 to replicate this share to box 2, - under Maintenance -> Backup -> Data Replication -> we've left the "Replication whole files" check box unchecked (Log replication errors and Use ACL are still checked).
However when a large file (15GB) is being amended on box1, I can see it copying the whole 15GB file to box2.