Help! about VM From File Level Move Block Level

Hello

Today i have create new VMs in NetAPP NFS Storage (the vm not data and OS  / 100G Thin Disk)

i move vm from Netapp NFS DataStore(File Level) to HP FC DataStore(Block Level) is very Slow ,

i see traffic is very busy~ need have 10 ~15 min is close session

but I create new NetApp ISCSI DataStore and new VM (the vm not data and OS  / 100G Thin Disk) than move to HP Storage is ver fast  about 5~10 sec is close session

how can i do??

My Environment

VMWare vCenter and ESXI is 5.5 u1

NetAPP ONTAP 8.2.1 7-Mode(HA Pair)

Install NFS For VAAI and Netapp VSC Plug-in