Raid 0 下面DD出来仅2.5MB/s?

fktol

CentOS 6.0 with Raid 0

1. [root@test ~]# dd if=/dev/zero of=test bs=64k count=4k oflag=dsync
   
2. ^C124+0 records in
   
3. 124+0 records out
   
4. 8126464 bytes (8.1 MB) copied, 3.3087 seconds, 2.5 MB/s

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这个神马问题。

1. [root@test ~]# dd if=/dev/zero of=./test.bin bs=1M count=256 conv=fsync
   
2. 256+0 records in
   
3. 256+0 records out
   
4. 268435456 bytes (268 MB) copied, 2.82364 seconds, 95.1 MB/s
   
5. [root@test ~]#
   
6. [root@test ~]# dd if=./test.bin of=/dev/zero bs=1M count=256 iflag=direct
   
7. 256+0 records in
   
8. 256+0 records out
   
9. 268435456 bytes (268 MB) copied, 2.44573 seconds, 110 MB/s

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收到了回复,

Hello,

The dsync flag will slow down the test with thousands of extra syncs - this isn't appropriate for testing raw write speed. If you'd like to test the raw write speed of the raid set then you can dd directly over the meta device (note that this will destroy the data on the /raid0/ partition - so do it only if you don't have any critical data there). Something like:

----
umount /raid0

dd if=/dev/zero of=/dev/md2 bs=64k count=128k
----


After you're done you will need to recreate the /raid0 filesystem and remount it:

----
mkfs.ext4 /dev/raid0

mount /raid0
----

Regards.


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[ 本帖最后由 fktol 于 2011-10-20 11:16 编辑 ]

onepx

我一直怀疑dd命令测的是什么，我也有楼上的情况，企业级硬盘，raid卡，dd出来2m...

瘦够了

我也是这个情况，3块300G的SAS做raid0，跑出来只有几M，蛋疼

Kvm

让你格式成ext4再看看速度

fktol

原帖由 ATOM 于 2011-10-20 08:59 发表
raid1的话会是几M的，我的是softriad1.

Raid0.~

tobeychan

跟机器的内核有关系的

mapleaf

问题大了

ATOM

raid1的话会是几M的，我的是softriad1.

cquyf

这么少