Copying data to network share

[Djinni]

Ok,
I'm trying to move 70GB of files and folders from my fathers desktop to a network share (which has a little over 7TB of free disk space)
But I keep getting the error:

"There is not enough space on Backup Space. You need an additional 64.2 GB to copy these files."

There are no quotas or user limits set.

The originating OS is Win7 and the destination OS is Win8.1

Anyone have any thoughts?

[fixx]

Samba shares on linux NAS servers are known to bug out like that sometimes (depending on what filesystem the drives are or what version of Samba) but no clue about Windows server.

[Djinni]

destination is windows 8.1
the drives are spanned in windows disk management
drives currently consist of:
2x WD 4tb red
2x WD 3tb red


Having issues with the MB getting it to read the other 4 sata ports... so getting the board replaced soon(ish) but otherwise I haven't had an issue with it.

I also say NAS, its more of a purpose built PC from old/cheap parts.