Dell1950 raid0 IO

有点令人困惑

1.write

第一次
[root@crdb11gstd home]# time dd if=/dev/zero of=/home/dell1950_w bs=4k count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 21.3064 seconds, 192 MB/s

real 0m21.308s
user 0m0.477s
sys 0m9.540s

后面几次
[root@crdb11gstd home]# time dd if=/dev/zero of=/home/dell1950_w bs=4k count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 10.1052 seconds, 405 MB/s

real 0m10.107s
user 0m0.465s
sys 0m9.639s

2 read write
第一次

[root@crdb11gstd home]# time dd if=/home/dell1950_w of=/home/dell1950_rw bs=4k count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 103.937 seconds, 39.4 MB/s

real 1m43.938s
user 0m0.499s
sys 0m12.467s

后面几次
[root@crdb11gstd home]# time dd if=/home/dell1950_w of=/home/dell1950_rw3 bs=4k count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 11.9869 seconds, 342 MB/s

real 0m11.988s
user 0m0.484s
sys 0m11.500s


3 read
[root@crdb11gstd home]# time dd if=/home/dell1950_w of=/dev/null bs=4k count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 2.40624 seconds, 1.7 GB/s

real 0m2.408s
user 0m0.365s
sys 0m2.043s