``Size on disk`` and ``Size``

Hi there

I have my customer saying ``Size on disk`` and ``size `` in windows folder properties are different for the data mount from Data Domain .

This is the number on customer site .

◆FOLDER in Windows local disk

     - size ： 1.19 GB

     - size on disk： 1.20 GB

◆FOLDER backed up by DD

     - size ： 1.19 GB

     - size on disk ： 4.51 GB

Its showing size on disk is bigger than size

Also for individual file size

◆File in Windows local disk

     Size ： 7.55 KB

     -file size on disk ： 8.00 KB

◆File backed up by DD

     - size ： 7.55 KB

     - File size on disk ： 1.00 MB

I can understand that this could be OS issue if actual volume is on Windows local disk .. like this blog ..

http://www.fixedbyvonnie.com/2014/08/whats-difference-file-size-size-disk/#.Vn4Loa3UjxR

But why this size difference in ``Size on disk`` with DD volume …Is there any good KB or explanation for it ?

Found in Isilon but not in DD ECN ….

Please help!

ref screenshot .... this is I am talking about ,here ,,,

Thanks !