RE: How to recreate a dmraid RAID array with mdadm (was: no subject)
> On Wed, 17 Nov 2010 12:26:47 +1100 wrote:
>>
>>> On Mon, 15 Nov 2010 16:21:22 +1100 wrote:
>>>> On Sun, 14 Nov 2010 01:50:42 -0500 Mike wrote:
>>>>
>>>> How does one fix the problem of not having the array not starting at boot?
>>>>
>>>
>>> To be able to answer that one would need to know exactly what is in the
>>> initramfs. And unfortunately all distros are different and I'm not
>>> particularly familiar with Ubuntu.
>>>
>>> Maybe if you
>>> mkdir /tmp/initrd
>>> cd /tmp/initrd
>>> zcat /boot/initrd.img-2.6.32-5-amd64 | cpio -idv
>>>
>>> and then have a look around and particularly report etc/mdadm/mdadm.conf
>>> and anything else that might be interesting.
>>>
>>> If the mdadm.conf in the initrd is the same as in /etc/mdadm, then it
>>> *should* work.
>>>
>>
>> Thanks again Neil. I got a chance to examine my systems initramfs to discover two differences in the local copy of mdadm.conf and the initramfs's copy.
>>
>> The initramfs's copy contains:
>>
>> DEVICE partitions
>> HOMEHOST
>> ARRAY metadata=imsm UUID=084b969a:0808f5b8:6c784fb7:62659383
>> ARRAY /dev/md/OneTB-RAID1-PV container=084b969a:0808f5b8:6c784fb7:62659383 member=0 UUID=ae4a1598:72267ed7:3b34867b:9c56497a
>>
>> So both ARRAY lines got copied over to the initramfs's copy of mdadm.conf, but
>>
>> CREATE owner=root group=disk mode=0660 auto=yes
>>
>> and
>>
>> MAILADDR root
>>
>> were not carried over on the update-initramfs command.
>>
>>
>> To your clearly better understanding of all this, does the CREATE stanza NEED to be present in the initramfs's copy of mdadm.conf in order for the array to be created on boot? If so, how can one accomplish this, so that the line is added whenever a new initramfs is created for the kernel?
>
> No, those differences couldn't explain it not working.
>
> I would really expect that mdadm.conf file to successfully assemble the
> RAID1.
>
> As you have the same in /etc/mdadm/mdadm.conf you could see what is happening
> by:
>
> mdadm -Ss
>
> to stop all md arrays, then
>
> mdadm -Asvv
>
> to auto-start everything in mdadm.conf and be verbose about that is happening.
>
> If that fails to start the raid1, then the messages it produces will be
> helpful in understanding why.
> If it succeeds, then there must be something wrong with the initrd...
> Maybe '/sbin/mdmon' is missing... Or maybe it doesn't run
> mdadm -As
> (or equivalently: mdadm --assemble --scan)
> but doesn't something else. To determine what you would need to search for
> 'mdadm' in all the scripts in the initrd and see what turns up.
>
Using mdadm -Ss stops the array:
mdadm: stopped /dev/md127
Where /dev/md127 is the imsm0 device and not the OneTB-RAID1-PV device.
Then executing mdadm -Asvv shows:
mdadm: looking for devices for further assembly
mdadm: no RAID superblock on /dev/dm-3
mdadm: /dev/dm-3 has wrong uuid.
mdadm: no RAID superblock on /dev/dm-2
mdadm: /dev/dm-2 has wrong uuid.
mdadm: no RAID superblock on /dev/dm-1
mdadm: /dev/dm-1 has wrong uuid.
mdadm: no RAID superblock on /dev/dm-0
mdadm: /dev/dm-0 has wrong uuid.
mdadm: no RAID superblock on /dev/loop0
mdadm: /dev/loop0 has wrong uuid.
mdadm: cannot open device /dev/sdc7: Device or resource busy
mdadm: /dev/sdc7 has wrong uuid.
mdadm: cannot open device /dev/sdc6: Device or resource busy
mdadm: /dev/sdc6 has wrong uuid.
mdadm: cannot open device /dev/sdc5: Device or resource busy
mdadm: /dev/sdc5 has wrong uuid.
mdadm: no RAID superblock on /dev/sdc2
mdadm: /dev/sdc2 has wrong uuid.
mdadm: cannot open device /dev/sdc1: Device or resource busy
mdadm: /dev/sdc1 has wrong uuid.
mdadm: cannot open device /dev/sdc: Device or resource busy
mdadm: /dev/sdc has wrong uuid.
mdadm: cannot open device /dev/sdb: Device or resource busy
mdadm: /dev/sdb has wrong uuid.
mdadm: cannot open device /dev/sda: Device or resource busy
mdadm: /dev/sda has wrong uuid.
mdadm: looking for devices for /dev/md/OneTB-RAID1-PV
mdadm: no recogniseable superblock on /dev/dm-3
mdadm/dev/dm-3 is not a container, and one is required.
mdadm: no recogniseable superblock on /dev/dm-2
mdadm/dev/dm-2 is not a container, and one is required.
mdadm: no recogniseable superblock on /dev/dm-1
mdadm/dev/dm-1 is not a container, and one is required.
mdadm: no recogniseable superblock on /dev/dm-0
mdadm/dev/dm-0 is not a container, and one is required.
mdadm: no recogniseable superblock on /dev/loop0
mdadm/dev/loop0 is not a container, and one is required.
mdadm: cannot open device /dev/sdc7: Device or resource busy
mdadm/dev/sdc7 is not a container, and one is required.
mdadm: cannot open device /dev/sdc6: Device or resource busy
mdadm/dev/sdc6 is not a container, and one is required.
mdadm: cannot open device /dev/sdc5: Device or resource busy
mdadm/dev/sdc5 is not a container, and one is required.
mdadm: no recogniseable superblock on /dev/sdc2
mdadm/dev/sdc2 is not a container, and one is required.
mdadm: cannot open device /dev/sdc1: Device or resource busy
mdadm/dev/sdc1 is not a container, and one is required.
mdadm: cannot open device /dev/sdc: Device or resource busy
mdadm/dev/sdc is not a container, and one is required.
mdadm: cannot open device /dev/sdb: Device or resource busy
mdadm/dev/sdb is not a container, and one is required.
mdadm: cannot open device /dev/sda: Device or resource busy
mdadm/dev/sda is not a container, and one is required.
So I am not really sure if that succeed or not, but it doesn't look like it has because there is not /dev/md/OneTB-RAID1-PV:
ls -al /dev/md/
total 0
drwxr-xr-x 2 root root 60 Nov 16 21:08 .
drwxr-xr-x 21 root root 3440 Nov 16 21:08 ..
lrwxrwxrwx 1 root root 8 Nov 16 21:08 imsm0 -> ../md127
But after mdadm -Ivv /dev/md/imsm0:
mdadm: UUID differs from /dev/md/OneTB-RAID1-PV.
mdadm: match found for member 0
mdadm: Started /dev/md/OneTB-RAID1-PV with 2 devices
Then ls -al /dev/md/ reveals /dev/md/OneTB-RAID1-PV:
total 0
drwxr-xr-x 2 root root 80 Nov 16 21:40 .
drwxr-xr-x 21 root root 3480 Nov 16 21:40 ..
lrwxrwxrwx 1 root root 8 Nov 16 21:08 imsm0 -> ../md127
lrwxrwxrwx 1 root root 8 Nov 16 21:40 OneTB-RAID1-PV -> ../md126
Regardless some initram disk findings:
pwd
/tmp/initrd
Then:
find . -type f | grep md | grep -v amd
./lib/udev/rules.d/64-md-raid.rules
./scripts/local-top/mdadm
./etc/mdadm/mdadm.conf
./conf/conf.d/md
./sbin/mdadm
./lib/udev/rules.d/64-md-raid.rules
http://paste.debian.net/100016/
./scripts/local-top/mdadm
http://paste.debian.net/100017/
./etc/mdadm/mdadm.conf
http://paste.debian.net/100018/
./conf/conf.d/md
http://paste.debian.net/100019/
./sbin/mdadm
{of course is a binary}
-M
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