How to properly erase entire block device /dev/xxxx?

I have a block device that I'm trying to erase using dd. Seems like all my portion has been deleted. However, dd command is returning No space left on device. Block device information is as follows, fdisk -l /dev/xxxx Disk /dev/xxxx: 7876 MB, 7876902912 bytes 4 heads, 16 sectors/track, 240384 cylinders Units = cylinders of 64 * 512 = 32768 bytes Disk /dev/xxxx doesn't contain a valid partition table I use the following dd command to erase, ~ # dd if=/dev/zero of=/dev/xxxx bs=1M count=7876 And I get the following output, dd: writing '/dev/xxxx': No space left on device 7513+0 records in 7512+0 records out 7876902912 bytes (7.3GB) copied, 355.751103 seconds, 21.1MB/s Can someone help me understand the output here, please? Output shows 7876902912 bytes (7.3GB) copied. This is the entire size of the device. Then does it mean that the entire device has been erased and since there is no space left, thus 'No space left on device'? or does it mean something else?