The DS214+ does not support VAAI or other storage acceleration for virtualization. So I doubt the plain DS214 would. Synology VAAI support is limited to iSCSI. From experience it makes VM migration, snapshots, etc perform much better than NFS. I have never saw or did a comparison between VAAI vs iSCSI vs NFS. I know NFS iops is superior to plain iSCSI, but the gap has been significantly closed in the last few DSM 5.0 updates.