Re: "A Nasty md/raid bug"

[NeilBrown <neilb@suse.de>]

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On Sat, 21 Jul 2012 16:16:07 +0200 "Peter Modrala" <x3m2@centrum.sk> wrote:

> Hi,
>  
> I firstly installed ubuntu server 12.04 and set up LVM on top of RAID1. After several days the system wasn't able to boot. RAID array was broken. Then I found this bug on your page:
> http://neil.brown.name/blog/20120615073245
> Then I decided to install newest ubuntu alternate which provides 3.5.0-5 version of kernel. After instalation's very first reboot I got the same messages as previously.
> I also installed linux-source-3.5.0 to verify the bug was fixed in this version of kernel.

If I understand correctly you simply gave up on the original installation,
didn't want to recovery any data of the array, and just installed a new
version of Ubuntu.  Is that correct?

In that case this is definitely a different problem, and the further details
you provided seem to confirm this.

I gather that your aren't using the md/raid1 array for the root filesystem so
the machine boot ups reasonably OK, it is just that the array isn't assembled
properly.  Correct?

So we need to treat this as a new problem:
  You installed some new Ubuntu distro and it didn't set up the arrays
  properly.

I would suggest that your best bet is to ask for support in some Ubuntu forum.

However if you can provide the exact details of the error you receive when
you boot, then I might be able to suggest something.

Alternately if I misunderstood your problem description, please help me
understand exactly what happened.

>  
> I can provide you root access if you want to check anything on my server.

I'd rather avoid that if possible.  Let's start with precise error messages.

NeilBrown






>  
> Thank You
>  
> Martin
>  
> ---
>  
> # uname -a
> Linux rat 3.5.0-5-generic #5-Ubuntu SMP Tue Jul 17 16:17:55 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
>  
> linux-source-3.5.0/drivers/md/md.c:
> ...
> static int md_notify_reboot(struct notifier_block *this,
>  unsigned long code, void *x)
> {
>  struct list_head *tmp;
>  struct mddev *mddev;
>  int need_delay = 0;
> 
>  for_each_mddev(mddev, tmp) {
>  if (mddev_trylock(mddev)) {
>  if (mddev->pers)
>  __md_stop_writes(mddev);
>  mddev->safemode = 2;
>  mddev_unlock(mddev);
>  }
>  need_delay = 1;
>  }
>  /*
>  * certain more exotic SCSI devices are known to be
>  * volatile wrt too early system reboots. While the
>  * right place to handle this issue is the given
>  * driver, we do want to have a safe RAID driver ...
>  */
>  if (need_delay)
>  mdelay(1000*1);
> 
>  return NOTIFY_DONE;
> } 
> ...
>  
>  
> # update-grub
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> Generating grub.cfg ...
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> Found linux image: /boot/vmlinuz-3.5.0-5-generic
> Found initrd image: /boot/initrd.img-3.5.0-5-generic
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> Found linux image: /boot/vmlinuz-3.5.0-5-generic
> Found initrd image: /boot/initrd.img-3.5.0-5-generic
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> error: unknown LVM metadata header.
> Found memtest86+ image: /boot/memtest86+.bin
> done
>  
>  
> # mdadm -Evvvvs
> mdadm: No md superblock detected on /dev/dm-3.
> mdadm: No md superblock detected on /dev/dm-2.
> mdadm: No md superblock detected on /dev/dm-1.
> mdadm: No md superblock detected on /dev/dm-0.
> mdadm: No md superblock detected on /dev/md/0.
> mdadm: No md superblock detected on /dev/sdb5.
> /dev/sdb2:
>  MBR Magic : aa55
> Partition[0] : 683800576 sectors at 2 (type 8e)
> /dev/sdb1:
>  Magic : a92b4efc
>  Version : 1.2
>  Feature Map : 0x0
>  Array UUID : dec31ddc:13aa86e0:d0635ca8:b630b4a5
>  Name : rat:0 (local to host rat)
>  Creation Time : Fri Jul 20 23:11:14 2012
>  Raid Level : raid1
>  Raid Devices : 2
> 
>  Avail Dev Size : 292704256 (139.57 GiB 149.86 GB)
>  Array Size : 146352000 (139.57 GiB 149.86 GB)
>  Used Dev Size : 292704000 (139.57 GiB 149.86 GB)
>  Data Offset : 262144 sectors
>  Super Offset : 8 sectors
>  State : clean
>  Device UUID : a9e91e4b:550235d5:de6f6a16:44d74be1
> 
>  Update Time : Sat Jul 21 16:06:32 2012
>  Checksum : c91e067d - correct
>  Events : 26
> 
> 
>  Device Role : Active device 1
>  Array State : AA ('A' == active, '.' == missing)
> /dev/sdb:
>  MBR Magic : aa55
> Partition[0] : 292966400 sectors at 2048 (type fd)
> Partition[1] : 683800578 sectors at 292970494 (type 05)
> mdadm: No md superblock detected on /dev/sda5.
> /dev/sda2:
>  MBR Magic : aa55
> Partition[0] : 683800576 sectors at 2 (type 8e)
> /dev/sda1:
>  Magic : a92b4efc
>  Version : 1.2
>  Feature Map : 0x0
>  Array UUID : dec31ddc:13aa86e0:d0635ca8:b630b4a5
>  Name : rat:0 (local to host rat)
>  Creation Time : Fri Jul 20 23:11:14 2012
>  Raid Level : raid1
>  Raid Devices : 2
> 
>  Avail Dev Size : 292704256 (139.57 GiB 149.86 GB)
>  Array Size : 146352000 (139.57 GiB 149.86 GB)
>  Used Dev Size : 292704000 (139.57 GiB 149.86 GB)
>  Data Offset : 262144 sectors
>  Super Offset : 8 sectors
>  State : clean
>  Device UUID : 458f63c4:1a882d4d:1ce3c46c:b0da0244
> 
>  Update Time : Sat Jul 21 16:06:32 2012
>  Checksum : 736ca887 - correct
>  Events : 26
> 
> 
>  Device Role : Active device 0
>  Array State : AA ('A' == active, '.' == missing)
> /dev/sda:
>  MBR Magic : aa55
> Partition[0] : 292966400 sectors at 2048 (type fd)
> Partition[1] : 683800578 sectors at 292970494 (type 05)
> 
> 
>  
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