磁盘测试：
写速度
$dd if=/dev/zero bs=1k count=1000000 of=1Gb.file
1000000+0 records in
1000000+0 records out
1024000000 bytes (1.0 GB) copied, 5.13676 seconds, 199 MB/s
读速度
$dd if=1Gb.file bs=64k |dd of=/dev/null
[haibo@localhost ~]$ dd if=1Gb.file bs=64k |dd of=/dev/null
15625+0 records in
15625+0 records out
1024000000 bytes (1.0 GB) copied, 6.37813 seconds, 161 MB/s
2000000+0 records in
2000000+0 records out
1024000000 bytes (1.0 GB) copied, 6.37891 seconds, 161 MB/s
读写速度
$dd if=1Gb.file of=2Gb.file bs=64k
15625+0 records in
15625+0 records out
1024000000 bytes (1.0 GB) copied, 2.21364 seconds, 463 MB/、