mkraid hangs system

mkraid hangs system

[Arnab Chowdry]

Hello all,

I know there's a similar thread created a few days ago, but I think my
situation might be different. I'm setting up a software RAID for my lab, and
I've run into no end of problems.

The RAID setup I'm going for is a 1+0 using four IDE disks. Each disk is
connected to a unique controller on two Promise PCI cards. Due to some
hardware problems with the motherboard, the system crashed during an initial
RAID reconstruction. Now that I've worked out the hardware problems with the
motherboard, the system hangs whenever I try to mkraid.

The system hangs within the first few seconds of mkraid, after it says that
it's analyzing the superblock. I've tried mkraid --really-force, tried
partitioning the drives using fdisk, and even tried to reset their MBR's.
Nothing seems to help the problem. 

I suspect it's some sort of corruption on the drives because of the original
crash that the RAID layer can't handle...so I'm wondering if there's some
way to wipe the drives completely and start from scratch again? Or if there
are any other suggestions?

I'm using Mandrake 9.2 with raidtools installed using urpmi.

Thanks,
Arnab Chowdry

Re: mkraid hangs system

[Luca Berra]

On Wed, May 12, 2004 at 11:21:32AM -0700, Arnab Chowdry wrote:
>I suspect it's some sort of corruption on the drives because of the original
>crash that the RAID layer can't handle...so I'm wondering if there's some
>way to wipe the drives completely and start from scratch again? Or if there
>are any other suggestions?
>
>I'm using Mandrake 9.2 with raidtools installed using urpmi.
>
you could dd if=/dev/zero of=/dev/your/disk,
or you can just try removing the superblock by installing mdadm from
contribs and using the --zero-superblock option.

L.

-- 
Luca Berra -- bluca@comedia.it
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RE: mkraid hangs system

[Arnab Chowdry]

>you could dd if=/dev/zero of=/dev/your/disk,

Oddly enough, dd hangs as well. I guess that means it's not a RAID problem.
Very strange though, and I don't have a good intuition about why it's
happening.

dd if=/dev/zero of=/dev/hde 
dd if=/dev/zero of=/dev/hdg
dd if=/dev/zero of=/dev/hdi
dd if=/dev/zero of=/dev/hdk

All of the above hang the system after a few seconds. I'm sorry is this is
now off-topic, but maybe some of you experts have some intuition about why
this might happen? All four of the drives can't have "gone bad" or
something.

-Arnab

RE: mkraid hangs system

[Guy]

These dd commands may take an hour or more.  You sure your system was hung?

Anyway, try this dd command on your working disks:
dd if=/dev/<good disk> of=/dev/null bs=64k

example:
	dd if=/dev/hda of=/dev/null bs=64k

or this if you want to know how long it takes:
	time dd if=/dev/hda of=/dev/null bs=64k

The above is a read test.  It will not overwrite any data.

Once you know your good disks work, try a bad disk.  Maybe you will be able
to determine a common hardware component, like a disk controller.

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Arnab Chowdry
Sent: Wednesday, May 12, 2004 6:27 PM
To: linux-raid@vger.kernel.org
Subject: RE: mkraid hangs system

>you could dd if=/dev/zero of=/dev/your/disk,

Oddly enough, dd hangs as well. I guess that means it's not a RAID problem.
Very strange though, and I don't have a good intuition about why it's
happening.

dd if=/dev/zero of=/dev/hde 
dd if=/dev/zero of=/dev/hdg
dd if=/dev/zero of=/dev/hdi
dd if=/dev/zero of=/dev/hdk

All of the above hang the system after a few seconds. I'm sorry is this is
now off-topic, but maybe some of you experts have some intuition about why
this might happen? All four of the drives can't have "gone bad" or
something.

-Arnab

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Re: mkraid hangs system

[Michel Wilson]

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On Wed, May 12, 2004 at 03:27:28PM -0700, Arnab Chowdry wrote:
> >you could dd if=/dev/zero of=/dev/your/disk,
> 
> Oddly enough, dd hangs as well. I guess that means it's not a RAID problem.
> Very strange though, and I don't have a good intuition about why it's
> happening.
> 
> dd if=/dev/zero of=/dev/hde 
> dd if=/dev/zero of=/dev/hdg
> dd if=/dev/zero of=/dev/hdi
> dd if=/dev/zero of=/dev/hdk
> 
> All of the above hang the system after a few seconds. I'm sorry is this is
> now off-topic, but maybe some of you experts have some intuition about why
> this might happen? All four of the drives can't have "gone bad" or
> something.
> 
> -Arnab
> 
You can try running one of those commands in the background (append a &,
or press ^Z and run 'bg') and then look at the output of 'vmstat 1'.
This will show you the amount of data written per second through the
block layer. If nothing is written, something is indeed wrong.
-- 
Michel Wilson     michel@crondor.net
PGP key ID        0xD2CB4B7E

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