dd if=/dev/zero of=benchmark bs=1M count=2048 conv=fdatasync 2048+0 records in 2048+0 records out 2147483648 bytes (2.1 GB, 2.0 GiB) copied, 2.54222 s, 845 MB/s dd if=/dev/zero of=benchmark bs=64k count=32k conv=fdatasync 32768+0 records in 32768+0 records out 2147483648 bytes (2.1 GB, 2.0 GiB) copied, 5.22697 s, 411 MB/s