target:~ # dd if=/dev/zero of=/dev/sdb bs=4096
dd: writing `/dev/sdb': No space left on device
250001+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 5.711 s, 179 MB/s
target:~ # dd if=/dev/zero of=/tmp/test bs=4096 count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 10.7513 s, 381 MB/s