#53 3TB Disks formats to 747 GB

[mclien]

I try to get a new 3TB HDD formatted with UDF. I used Debian7 and systemrescueCD (gentoo) for that, in both cases with the following command:
mkudffs --media-type=hd /dev/sdX
Both times it went trough without errors. But after mounting the drive df reports it to be 747 or 787GB.
(Versions of mkudffs will be provided later, not at hand at the moment).
Is there a general limit to UDF, which I didn't recognized?