Comment 1 for bug 793534

Do you see a printed message like "Operation not supported" when backing up if you run deja-dup from a Terminal? I suspect this is because some NAS drives over SMB don't report how much free space there is.

For example, see bug 657518 where we had a previous problem that Deja Dup assumed zero space available if the NAS didn't report any. Now we assume there is space, just to let you continue.

To test if this is the case for you, can you report the results of the following?

sudo apt-get install gvfs-bin
gvfs-info -f smb://blargblarg