Are you 100% sure, on selecting [/dev/sdb] (y/n)? y

Debug: ARM rootfs: armhf-rootfs-debian-wheezy.tar
Debug: image has initrd.img:
Debug: image has device tree:
Debug: /sbin/fdisk version:
fdisk (util-linux-ng 2.17.2)

Unmounting Partitions
-----------------------------
Zeroing out Partition Table
1024+0 records in
1024+0 records out
1048576 bytes (1.0 MB) copied, 0.348532 s, 3.0 MB/s