Windows Server 2012 R2 iSCSI LUN (from QNAP) deduplication setup ?

Hi People,

I'd like to provision iSCSI LUN for my QNAP TS-EC1280U running QT OS v4.2.0 NAS, so that I can utilize the Windows Server 2012 R2 NTFS data deduplication feature.

The presented disk LUN will be formatted with the below specification from Windows:

File System: NTFS
GUID Partition Table (GPT) for more than 2 TB support
File Allocation Size: default NTFS 4 KB

is that possible with the above parameter or shall I change it to the largest allocation size to 64 KB ?

Is it possible to extend the size of the LUN later on from the web console from 2 TB to 10 TB without losing the data later on ?

Thanks.