Creating failed-mode RAID1 with mdadm

Creating failed-mode RAID1 with mdadm

[Ross Vandegrift]

Hey everyone,

	Creating a new array today, I decided I should probably start
using mdadm instead of the old tools.  I've been using it a bit at home
to do minor things, and it seemed nice.
	I've got a box with two 20G ide drives installed.  One is
currently the root drive at /dev/hda1 and the other is one of the disks
for the mirrored pair at /dev/hde1.  I'm trying to create the array with
/dev/hdg1 as a failed disk, and then move /dev/hda to /dev/hde after I
start booting the machine off of /dev/md0.
	When I do:

# mdadm --create /dev/md0 --level 1 --raid-disks=2 /dev/hde1 /dev/hdg1

I get:

mdadm: Cannot open /dev/hdg1: No such device or address
mdadm: create aborted

This makes sense, as /dev/hdg doesn't really exist yet.  I've tried
doing:

# mdadm --set-faulty /dev/md0 /dev/hdg1

but it doesn't seem to help.  How can I build an array like this via
mdadm?

Ross Vandegrift
ross@willow.seitz.com

Re: Creating failed-mode RAID1 with mdadm

[Ross Vandegrift]

> # mdadm --create /dev/md0 --level 1 --raid-disks=2 /dev/hde1 /dev/hdg1
> 
> I get:
> 
> mdadm: Cannot open /dev/hdg1: No such device or address
> mdadm: create aborted

Hmmm, funny - as it turns out, mdadm actually created the array and
started it with /dev/hdg1 failed.  It just said it didn't.

Ross Vandegrift
ross@willow.seitz.com

Re: Creating failed-mode RAID1 with mdadm

[Neil Brown]

On Tuesday April 30, ross@willow.seitz.com wrote:
> > # mdadm --create /dev/md0 --level 1 --raid-disks=2 /dev/hde1 /dev/hdg1
> > 
> > I get:
> > 
> > mdadm: Cannot open /dev/hdg1: No such device or address
> > mdadm: create aborted
> 
> Hmmm, funny - as it turns out, mdadm actually created the array and
> started it with /dev/hdg1 failed.  It just said it didn't.

That surprises me?   Are you in a position to try it again and see?
If so, what version of mdadm?

NeilBrown

Re: Creating failed-mode RAID1 with mdadm

[bo]

Try with
# mdadm --create /dev/md0 --level 1 --raid-disks=2 /dev/hde1 missing

It will work.


----- Original Message ----- 
From: "Ross Vandegrift" <ross@willow.seitz.com>
To: <linux-raid@vger.kernel.org>
Sent: Tuesday, April 30, 2002 11:48 AM
Subject: Creating failed-mode RAID1 with mdadm


> Hey everyone,
> 
> Creating a new array today, I decided I should probably start
> using mdadm instead of the old tools.  I've been using it a bit at home
> to do minor things, and it seemed nice.
> I've got a box with two 20G ide drives installed.  One is
> currently the root drive at /dev/hda1 and the other is one of the disks
> for the mirrored pair at /dev/hde1.  I'm trying to create the array with
> /dev/hdg1 as a failed disk, and then move /dev/hda to /dev/hde after I
> start booting the machine off of /dev/md0.
> When I do:
> 
> # mdadm --create /dev/md0 --level 1 --raid-disks=2 /dev/hde1 /dev/hdg1
> 
> I get:
> 
> mdadm: Cannot open /dev/hdg1: No such device or address
> mdadm: create aborted
> 
> This makes sense, as /dev/hdg doesn't really exist yet.  I've tried
> doing:
> 
> # mdadm --set-faulty /dev/md0 /dev/hdg1
> 
> but it doesn't seem to help.  How can I build an array like this via
> mdadm?
> 
> Ross Vandegrift
> ross@willow.seitz.com
> 
> -
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