root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 2.36389 s, 454 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 6.51472 s, 165 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 6.157 s, 174 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 5.54965 s, 193 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=10 oflag=direct
dd: error writing ‘here’: No space left on device
7+0 records in
6+0 records out
6442450944 bytes (6.4 GB) copied, 13.2924 s, 485 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=10 oflag=direct
dd: error writing ‘here’: No space left on device
7+0 records in
6+0 records out
6442450944 bytes (6.4 GB) copied, 13.6653 s, 471 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=10 oflag=direct
dd: error writing ‘here’: No space left on device
7+0 records in
6+0 records out
6442450944 bytes (6.4 GB) copied, 13.5847 s, 474 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=512M count=20 oflag=direct
dd: error writing ‘here’: No space left on device
13+0 records in
12+0 records out
6442450944 bytes (6.4 GB) copied, 13.7889 s, 467 MB/s

root@ubuntu:~# dd if=/dev/zero of=here bs=1G count=20 oflag=direct
dd: error writing ‘here’: No space left on device
7+0 records in
6+0 records out
6442450944 bytes (6.4 GB) copied, 14.0409 s, 459 MB/s