8.04 -> 10.04 /dev/md0 not created in intiramfs
 

Title: Signature




After an upgrade from 8.04 -> 10.04 my system is unable to boot.
After a lot of work it seems that the blocking problem is that /dev/md0
is not being created in initramfs so the volume group containing the /
file system is not being activated and therefore the boot fails at that
point.



In /sbin both mdadm and lmv exist and the arrays and volume groups can
be created manually using them. The system can then complete booting.
Updating initramfs after booting has no apparent effect.



Based on posts I have found I have tried adding raid=noautodetect and
rootdelay=240 to the GRUB kernel command line separately and together
with no effect, except delaying the boot.



It seems that udev is not running correctly so I began digging through
the udev rules but don't really understand how it actually works.



In /lib/udev/rules I found;

85_mdadm.rules

85_lmv2.rules


If I were guessing (and I am) I would expect 85_lvm2 to be run before
85_mdadm, which is the wrong order. I also found 56_lvm.rules which
doesn't seem to do anything.



I would appreciate pointers of testing these rules to see what the
problem is. It seems all of the pieces are there for this to wok
correctly but there is something missing.



How can I run or test a single rule? Which udevadm options test these
rules, so far I don't see udevadm test offering any help.



--



Robert
Steinmetz,
AIA

Principal

Steinmetz & Associates




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8.04 -> 10.04 /dev/md0 not created in intiramfs
 

> In /lib/udev/rules I found;
>
> 85_mdadm.rules
> 85_lmv2.rules
>
> If I were guessing (and I am) I would expect 85_lvm2 to be run before
> 85_mdadm, which is the wrong order. I also found 56_lvm.rules which
> doesn't seem to do anything.

mdadm should run before lvm. lvm can run on md devices and so lvm can
have a dependency on mdadm

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8.04 -> 10.04 /dev/md0 not created in intiramfs
 

I'm aware of that. Does this configuration* mean that mdadm is running
before lvm and if so how do I correct it?



On 7/8/2010 12:01 AM, Christopher Chan wrote:


In /lib/udev/rules I found;

85_mdadm.rules
85_lmv2.rules

If I were guessing (and I am) I would expect 85_lvm2 to be run before
85_mdadm, which is the wrong order. I also found 56_lvm.rules which
doesn't seem to do anything.



mdadm should run before lvm. lvm can run on md devices and so lvm can
have a dependency on mdadm




--







Robert
Steinmetz,
AIA

Principal

Steinmetz
& Associates



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8.04 -> 10.04 /dev/md0 not created in intiramfs
 

On Thursday, July 08, 2010 02:33 PM, Robert Steinmetz wrote:
> I'm aware of that. Does this configuration mean that mdadm is running
> before lvm and if so how do I correct it?

Oh, sorry, read your post wrong. I would have thought the lower number
gets priority but then i do not know udev all that well. Actually, I
doubt that udev is the problem given that it has been running from at
least Hardy to Lucid...

Does your initrd image at all package the md and lvm modules?


>
> On 7/8/2010 12:01 AM, Christopher Chan wrote:
>>> In /lib/udev/rules I found;
>>>
>>> 85_mdadm.rules
>>> 85_lmv2.rules
>>>
>>> If I were guessing (and I am) I would expect 85_lvm2 to be run before
>>> 85_mdadm, which is the wrong order. I also found 56_lvm.rules which
>>> doesn't seem to do anything.
>>>
>> mdadm should run before lvm. lvm can run on md devices and so lvm can
>> have a dependency on mdadm
>>
>
> --
> *Robert Steinmetz, AIA*
> Principal
> *Steinmetz & Associates*
>


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8.04 -> 10.04 /dev/md0 not created in intiramfs
 

Christopher Chan wrote:

On Thursday, July 08, 2010 02:33 PM, Robert Steinmetz wrote:


I'm aware of that. Does this configuration mean that mdadm is running
before lvm and if so how do I correct it?



Oh, sorry, read your post wrong. I would have thought the lower number
gets priority but then i do not know udev all that well. Actually, I
doubt that udev is the problem given that it has been running from at
least Hardy to Lucid...

Does your initrd image at all package the md and lvm modules?


I'm not that familiar with this part of Ubuntu. I'm not sure how to
check initrd or really even what to look for. When the startup fails
and I get dropped into the initramfs shell lvm and mdadm are there and
the raid arrays and volume groups can be easily assembled at the shell
comand line, from there I can boot the system. I'm taking that to mean
the appropriate modules are loaded although in /proc/modules I do not
see lvm, I do see the raid0 and raid1 modules I think are necessary for
md0 to work.



What is failing is the automatic activation of the Raid Array or
possibly something before that. The error I get indicates that the root
filesystem could not be located and checking /dev in initramfs it is
not there because md0 is not there so the volume groups cannot be there.



My understanding of how this works (short version) is that Grub loads
initramfs and the runs a number of startup scrips and rules are run
until
the system essentially chroot to the preferred root filesystem to
continue startup.



On 7/8/2010 12:01 AM, Christopher Chan wrote:



In /lib/udev/rules I found;

85_mdadm.rules
85_lmv2.rules

If I were guessing (and I am) I would expect 85_lvm2 to be run before
85_mdadm, which is the wrong order. I also found 56_lvm.rules which
doesn't seem to do anything.



mdadm should run before lvm. lvm can run on md devices and so lvm can
have a dependency on mdadm




--
*Robert Steinmetz, AIA*
Principal
*Steinmetz & Associates*











--


Signature
Robert
Steinmetz,
AIA

Principal

Steinmetz & Associates




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8.04 -> 10.04 /dev/md0 not created in intiramfs
 

I have worked around the problem by adding a script to Attach the
Arrays and Enable the volume groups



#!/bin/sh



echo "Attaching Arrays ..."

/sbin/mdadm -A --scan

/bin/sleep 1

echo "Enabling LVM .."

/sbin/lvm vgchange -ay


I placed the script in /etc/initramfs-tools and updated initramfs. It
boots now.

I still don't know why it wouldn't boot before





*Robert Steinmetz AIA wrote:



Christopher Chan wrote:

On Thursday, July 08, 2010 02:33 PM, Robert Steinmetz wrote:


I'm aware of that. Does this configuration mean that mdadm is running
before lvm and if so how do I correct it?


Oh, sorry, read your post wrong. I would have thought the lower number
gets priority but then i do not know udev all that well. Actually, I
doubt that udev is the problem given that it has been running from at
least Hardy to Lucid...

Does your initrd image at all package the md and lvm modules?


I'm not that familiar with this part of Ubuntu. I'm not sure how to
check initrd or really even what to look for. When the startup fails
and I get dropped into the initramfs shell lvm and mdadm are there and
the raid arrays and volume groups can be easily assembled at the shell
comand line, from there I can boot the system. I'm taking that to mean
the appropriate modules are loaded although in /proc/modules I do not
see lvm, I do see the raid0 and raid1 modules I think are necessary for
md0 to work.



What is failing is the automatic activation of the Raid Array or
possibly something before that. The error I get indicates that the root
filesystem could not be located and checking /dev in initramfs it is
not there because md0 is not there so the volume groups cannot be there.



My understanding of how this works (short version) is that Grub loads
initramfs and the runs a number of startup scrips and rules are run
until
the system essentially chroot to the preferred root filesystem to
continue startup.


On 7/8/2010 12:01 AM, Christopher Chan wrote:



In /lib/udev/rules I found;

85_mdadm.rules
85_lmv2.rules

If I were guessing (and I am) I would expect 85_lvm2 to be run before
85_mdadm, which is the wrong order. I also found 56_lvm.rules which
doesn't seem to do anything.



mdadm should run before lvm. lvm can run on md devices and so lvm can
have a dependency on mdadm



--
*Robert Steinmetz, AIA*
Principal
*Steinmetz & Associates*










--


Signature
Robert
Steinmetz,
AIA

Principal

Steinmetz & Associates






--


Signature
Robert
Steinmetz,
AIA

Principal

Steinmetz & Associates





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