PLEASE HELP!!! RAID problems with 10.04

Maxime Alarie malarie at
Tue Apr 13 14:09:49 UTC 2010

I had similar problem with 9.1.

My software raid 1 was working on a test server, then after an improper shutdown, the  raid was not detected anymore. I was dropped into init-ramfs at boot time and there was no way to  remount  the raid.  I found out that there was a bug in the software  raid array since 8.04 (did not test prior to this release).

I have  decided to backup all my data, re-install and use the 2nd disk as a backup disk (cronjob and rsync of important directories)

The only way I was able to mount the raid was with a Desktop Live CD. Once I've booted to the Live Setup, I downloaded  mdadm and rebuilt the raid array temporarily:  mdadm --scan --assemble /dev/md0.

Not sure if this can help you..  But now Ubuntu and software raids are a no-go for me.

Maxime Alarie 
Spécialiste IT / IT Specialist
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-----Original Message-----
From: ubuntu-users-bounces at [mailto:ubuntu-users-bounces at] On Behalf Of Fred Roller
Sent: Tuesday, April 13, 2010 7:32 AM
To: Ubuntu user technical support,not for general discussions
Subject: Re: PLEASE HELP!!! RAID problems with 10.04

On 04/13/2010 06:42 AM, Tom H wrote:
> On Mon, Apr 12, 2010 at 10:44 PM, NoOp<glgxg at>  wrote:
>> On 04/12/2010 07:16 PM, Alvin Thompson wrote:
>>> On Apr 12, 2010, at 7:25 PM, NoOp wrote:
>>>> Maybe related? From the release notes:
>>>><quote>  ... Activating a
>>>> RAID 1 array in degraded mode is reported to lead to RAID disks
>>>> being reported as in sync when they are not, resulting in data
>>>> loss. Since RAID 1 arrays will automatically be brought up in
>>>> degraded mode when a member disk is unavailable, users with
>>>> production software RAID 1 disks are advised not to upgrade to the
>>>> 10.04 LTS Beta until this bug is resolved. (557429)</quote>
>>> It's possible there are just a lot of problems with RAID right now,
>>> but this was RAID5, and since this was a pre-existing device, it was
>>> never in degraded mode.  I was also surprised to notice that the two
>>> devices I created during the install also did not appear to start in
>>> degraded mode (although they may have finished their re-sync before I
>>> noticed).
>> But you *did* read the release notes (including bug reports) *prior* to
>> trying 10.04... right? To be quite honest I'm clueless when it comes to
>> RAID. But I think that prior to trying 10.04 on a RAID, and having read
>> the release notes first, I'd be hesitant to try 10.04 until the issues
>> are/were resolved.
>> Suggest that you file a bug report on launchpad (no, not being facetious
>> here, I'm seriously suggesting you do this). Doing so may likely help
>> 10.04 final, and help sort out your issue.
> I had said on the OP 's first thread on this topic that according to
> the output that he had posted, his old array is OK. It may just be a
> case of assembling it before mounting it.
Perhaps this will help:

Start at section 4 and adjust for your system.  Either with a live 
distro boot or build on one of your 25G partitions.  I would do the 
latter with an older version of Ubuntu.  You could attempt to dd each 
disk as a form of back up if you have the hardware to do so.  The other 
option is to investigate professional data recovery services.

and this may help:

Create the RAID  arrays ¶

The RAID arrays will be made up of groups of partitions.

Install the Linux RAID package:

     apt-get install mdadm

First the mirror array for /boot, which will use the first partition on 
two disks on different IDE channels (to avoid master/slave bootlenecks):

     mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdc1
     mdadm: array /dev/md0 started.

Now create a mirror array for swap & hibernate:

     mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdd1
     mdadm: array /dev/md1 started.

All remaining space (in the second partition) is allocated to the RAID-5 
array. Its capacity will be the number of disks in the array minus one, 
multiplied by the size of the partition: (N - 1) x C : (4 - 1) x 58GB = 

     mdadm --create /dev/md2 --level=5 --raid-devices=4 /dev/sda2 
/dev/sdb2 /dev/sdc2 /dev/sdd2
     mdadm: array /dev/md2 started.

Check the array build status:

     cat /proc/mdstat
     Personalities : [raid1] [raid6] [raid5] [raid4]
     md2 : active raid5 sdd2[4] sdc2[2] sdb2[1] sda2[0]
           171332928 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]

     md1 : active raid1 sdd1[1] sdb1[0]
           2939776 blocks [2/2] [UU]
           [==========>..........]  resync = 54.2% (1594496/2939776) 
finish=0.6min speed=33434K/sec

     md0 : active raid1 sdc1[1] sda1[0]
           2939776 blocks [2/2] [UU]
       [==============>......]  resync = 74.1% (2179200/2939776) 
finish=0.3min speed=33574K/sec

     unused devices: <none>

Wait until the arrays are finished building. Press Ctrl+C to interrupt 
watch when all the arrays have finished building:

     watch -n 30 cat /proc/mdstat

     Personalities : [raid1] [raid6] [raid5] [raid4]
     md2 : active raid5 sdd2[3] sdc2[2] sdb2[1] sda2[0]
           171332928 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

     md1 : active raid1 sdd1[1] sdb1[0]
           2939776 blocks [2/2] [UU]

     md0 : active raid1 sdc1[1] sda1[0]
           2939776 blocks [2/2] [UU]

     unused devices: <none>

Again, if you have the hardware, dd (or ddrescue or similar) the drives 
and keep very good track of which is which.  You can re-fdisk the 
partitions and move the data back over in an attempt to save the data.  
If the data is /that/ critical I would suggest a professional data 
recovery service.


"Life is like linux, simple.  If you are fighting it you are doing something wrong."

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