[root@node2 ]# dd if=/dev/zero of=test bs=4k count=10 oflag=direct
10+0 records in
10+0 records out
40960 bytes (41 kB) copied, 0.0308499 s, 1.3 MB/s
[root@node2 ]# dd if=/dev/zero of=test bs=4k count=100 oflag=direct
100+0 records in
100+0 records out
409600 bytes (410 kB) copied, 0.393913 s, 1.0 MB/s
[root@node2 ]# dd if=/dev/zero of=test bs=4k count=200 oflag=direct
200+0 records in
200+0 records out
819200 bytes (819 kB) copied, 0.738993 s, 1.1 MB/s
[root@node2 ]# dd if=/dev/zero of=test bs=4k count=2000 oflag=direct
2000+0 records in
2000+0 records out
8192000 bytes (8.2 MB) copied, 7.26254 s, 1.1 MB/s
[root@node2 ]# dd if=/dev/zero of=test bs=4k count=4000 oflag=direct
4000+0 records in
4000+0 records out
16384000 bytes (16 MB) copied, 15.1711 s, 1.1 MB/s
[root@node2 ]# dd if=/dev/zero of=test bs=4k count=8000 oflag=direct
8000+0 records in
8000+0 records out
32768000 bytes (33 MB) copied, 29.6221 s, 1.1 MB/s