On Thu, Jan 28, 2010 at 09:31:23AM -0500, Yuehai Xu wrote:

quoted

quoted

md0 : active raid5 sdh1[7] sdg1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1] sdb1[0]
      631353600 blocks level 5, 64k chunk, algorithm 2 [7/6] [UUUUUU_]

[...]

I don't think any of my drive fail because there is no "F" in my
/proc/mdstat output

It's not failed, it's simply missing. Either it was unavailable when the
array was assembled, or you've explicitely created/assembled the array
with a missing drive.

How do you know my RAID5 array has one drive missing?

Look at the above output: there are just 6 of the 7 drives available,
and the underscore also means a missing drive. 

I tried to setup RAID5 with 5 disks, 3 disks, after each setup,
recovery has always been done.

Of course.

However, if I format my md0 with such command:
mkfs.ext3 -b 4096 -E stride=16 -E stripe-width=*** /dev/XXXX, the
performance for RAID5 becomes usual, at about 200~300M/s.

I suppose in that case you had all the disks present in the array.

Gabor

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     MTA SZTAKI Computer and Automation Research Institute
                Hungarian Academy of Sciences
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