thx but i met this problem.

i use 4 x 400GB SATA disks, i make a raid 0 or 5, and build a vg on top
of md, then use bonnie++ to test read performance.

LVM (MD = sda+sdb+..) = 95MBsec, md is built on top of whole disk.

LVM (MD = sda1+sdb1+.) = 48MBsec, md is built on top of each partition.

so where is the problem? does md chunk size matter? or lvm extent size
matters? thx.


ming

On Sat, 2004-10-23 at 02:07, Guy wrote:

I found this old message:
"On Tuesday June 1, maheshext3@yahoo.com wrote:

quoted

--- Neil Brown <neilb@cse.unsw.edu.au> wrote:

quoted

What does
   ls -l /dev/hd[eg]5
show? How about
   cat /proc/partitions
   dd if=/dev/hde5 of=/dev/null bs=1024k

Thanks a lot, Neil, turns out those nodes were not present. After I 
mknod'd them, all's fine in RAIDland...
  Quick question: does using extended partitions for RAID affect 
performance?

The fact that the partitions are "extended" is invisible to most of the
kernel, and it could not have any affect of performance.

NeilBrown"

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Ming Zhang
Sent: Friday, October 22, 2004 1:28 PM
To: linux-raid@vger.kernel.org
Subject: md on partition

Hi folks.

I remembered that there was a discussion on the list about some abnormal
performance penalty if u use a partition instead of a whole disk for MD.
But I could not find this discussion via archival or google.

Could somebody be kindly enough to point me to the right spot? Thanks a
lot.

Ming


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