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Old 12-31-2009, 03:23 PM
"Joseph L. Casale"
 
Default Lost mdadm.conf

>I've collected an howto somewhere from the 'net:
>
>$ cat docs/sysadm/mdadm_recovery.txt
>
>## define possible devices with arrays
>echo 'DEVICE /dev/hd[a-l]* /dev/sd[a-l]*' > mdadm.conf
>
>## scan
>mdadm --examine --scan --config=mdadm.conf >> mdadm.conf
>
>## review configuration, copy to /etc
>cp mdadm.conf /etc/
>
>## create devices
>MAKEDEV md || { for ((i=0; i <= 31; i++)); do mknod /dev/md$i b 9 $i; done; }
>
>## start arrays
>mdadm --assemble --scan

That's a fairly limited script and out of date, I've never used mknod...

Simply:
# mdadm --detail --scan --verbose
And look it over, then:
# mdadm --detail --scan --verbose > /etc/mdadm.conf

And worry about mountpoints etc now...
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Old 12-31-2009, 03:24 PM
robert mena
 
Default Lost mdadm.conf

Hi,
it worked (kind of). Thanks.
I was able to recreate (the all appear in /proc/mdstat) and in the rescue I've mounted the /boot which maps to /dev/md0. But I can't mount any other partition.

they all complain with the same error
mount: Mounting /dev/mdX on /tmp/mountpoint failed: no such file or directory

Any ideas?


On Thu, Dec 31, 2009 at 11:42 AM, Luciano Rocha <strange@nsk.no-ip.org> wrote:

On Thu, Dec 31, 2009 at 11:39:25AM -0400, robert mena wrote:

> Hi,

>

> I lost my mdadm.conf (and /proc/mdadm shows nothing useful) and I'd like to

> mount the filesystem again. *So I've booted using rescue but I was wondering

> if I can do a command like this safely (i.e without losing the data

> previously stored).

>

> mdadm -C /dev/md0 --level=raid0 --raid-devices=2 /dev/sda1 /dev/sdb1

>

> Where of course the raid devices and the /dev/x are the correct ones



I've collected an howto somewhere from the 'net:



$ cat docs/sysadm/mdadm_recovery.txt



## define possible devices with arrays

echo 'DEVICE /dev/hd[a-l]* /dev/sd[a-l]*' > mdadm.conf



## scan

mdadm --examine --scan --config=mdadm.conf >> mdadm.conf



## review configuration, copy to /etc

cp mdadm.conf /etc/



## create devices

MAKEDEV md || { for ((i=0; i <= 31; i++)); do mknod /dev/md$i b 9 $i;

done; }



## start arrays

mdadm --assemble --scan



Best of luck,



--

lfr

0/0


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Old 12-31-2009, 03:27 PM
James Bensley
 
Default Lost mdadm.conf

2009/12/31 Luciano Rocha <strange@nsk.no-ip.org>:
> On Thu, Dec 31, 2009 at 11:39:25AM -0400, robert mena wrote:
>> Hi,
>>
>> I lost my mdadm.conf (and /proc/mdadm shows nothing useful) and I'd like to
>> mount the filesystem again. *So I've booted using rescue but I was wondering
>> if I can do a command like this safely (i.e without losing the data
>> previously stored).
>>
>> mdadm -C /dev/md0 --level=raid0 --raid-devices=2 /dev/sda1 /dev/sdb1
>>
>> Where of course the raid devices and the /dev/x are the correct ones
>

I can't say this with 100% certainty but I would of thought that it
would been fine. I've lost my mdadm.conf (reinstalled OS) with a
separate 4 disk RAID 5 array and re-assembled the array and carried on
as if nothing had happened.

Use "sudo mdadm -E --scan" do get a list of discovered RAID devices
like this example:

ARRAY /dev/md0 level=raid0 num-devices=2 UUID=fde94900:3f3f3bf6

Pop the results in your mdadm.conf and that should sort you out after
a reboot (I think). Also try something like "sudo mdadm --assemble
/dev/md1
/dev/sdb1 /dev/sdc1" to assemble the RAID manually.

--
Regards,
James

Pablo Picasso - "Computers are useless. They can only give you
answers." - http://www.brainyquote.com/quotes/authors/p/pablo_picasso.html
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Old 12-31-2009, 03:31 PM
James Bensley
 
Default Lost mdadm.conf

Now you've got your array working give us a fuller picture, how many
hard drives have you got, in what configuration, how many arrays, how
many partitions, what file systems, output of "mount" command, fstab
details etc etc

--
Regards,
James

Jonathan Swift - "May you live every day of your life." -
http://www.brainyquote.com/quotes/authors/j/jonathan_swift.html
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Old 12-31-2009, 03:32 PM
Luciano Rocha
 
Default Lost mdadm.conf

On Thu, Dec 31, 2009 at 12:24:23PM -0400, robert mena wrote:
> Hi,
>
> it worked (kind of). Thanks.
>
> I was able to recreate (the all appear in /proc/mdstat) and in the rescue
> I've mounted the /boot which maps to /dev/md0. But I can't mount any other
> partition.
>
> they all complain with the same error
>
> mount: Mounting /dev/mdX on /tmp/mountpoint failed: no such file or
> directory

Silly question: does /dev/md0 and /tmp/mountpoint exist?

--
lfr
0/0
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Old 12-31-2009, 03:37 PM
Luciano Rocha
 
Default Lost mdadm.conf

On Thu, Dec 31, 2009 at 04:23:52PM +0000, Joseph L. Casale wrote:
>
> That's a fairly limited script and out of date, I've never used mknod...

Not all rescue environments have MAKEDEV or have it in $PATH, so this
should always work.

--
lfr
0/0
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Old 12-31-2009, 03:38 PM
robert mena
 
Default Lost mdadm.conf

Hi,
Yes. *
I have from /devmd0 to /dev/md6 (for some reason it skipped md3). *
I do not have the fstab at hand but */*/boot*
and /tmp*

each map to a different mdX. * I've been able to mount the /boot but no other.
One thing, besides the /boot all the other are ext4. *Could it be a problem with the rescue does not supporting this filesystem type.

On Thu, Dec 31, 2009 at 12:32 PM, Luciano Rocha <strange@nsk.no-ip.org> wrote:

On Thu, Dec 31, 2009 at 12:24:23PM -0400, robert mena wrote:

> Hi,

>

> it worked (kind of). Thanks.

>

> I was able to recreate (the all appear in /proc/mdstat) and in the rescue

> I've mounted the /boot which maps to /dev/md0. But I can't mount any other

> partition.

>

> they all complain with the same error

>

> mount: Mounting /dev/mdX on /tmp/mountpoint failed: no such file or

> directory



Silly question: does /dev/md0 and /tmp/mountpoint exist?



--

lfr

0/0


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Old 12-31-2009, 03:40 PM
Luciano Rocha
 
Default Lost mdadm.conf

On Thu, Dec 31, 2009 at 12:38:51PM -0400, robert mena wrote:
> Hi,
>
> Yes.
>
> I have from /devmd0 to /dev/md6 (for some reason it skipped md3).
>
> I do not have the fstab at hand but
> /
> /boot
> and /tmp
>
> each map to a different mdX. I've been able to mount the /boot but no
> other.
>
> One thing, besides the /boot all the other are ext4. Could it be a problem
> with the rescue does not supporting this filesystem type.

Yes, it could. Can you send us the output of dmesg?

--
lfr
0/0
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Old 12-31-2009, 03:40 PM
"Joseph L. Casale"
 
Default Lost mdadm.conf

>Not all rescue environments have MAKEDEV or have it in $PATH, so this should always work.

Really, on my hp's as well? I don't have any /dev/hdx or /dev/sdx on the ones with software raid...

Nothing is easier than simply:
# mdadm --detail --scan --verbose > /etc/mdadm.conf

And that actually *does* work in all environments...
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Old 12-31-2009, 03:43 PM
robert mena
 
Default Lost mdadm.conf

Dmesg shows (for example when I tried to mount /dev/md2)
*ext4-fs: md2 : not marked OK to use with test code

On Thu, Dec 31, 2009 at 12:40 PM, Luciano Rocha <strange@nsk.no-ip.org> wrote:

On Thu, Dec 31, 2009 at 12:38:51PM -0400, robert mena wrote:

> Hi,

>

> Yes.

>

> I have from /devmd0 to /dev/md6 (for some reason it skipped md3).

>

> I do not have the fstab at hand but

> /

> /boot

> and /tmp

>

> each map to a different mdX. * I've been able to mount the /boot but no

> other.

>

> One thing, besides the /boot all the other are ext4. *Could it be a problem

> with the rescue does not supporting this filesystem type.



Yes, it could. Can you send us the output of dmesg?



--

lfr

0/0


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