Re: Desperate: mdadm fails to assemble raid saying devices are busy.

[Sachin Garg <sgarg.bugreporter@gmail.com>]

Hi Roger & Mikael,

Thanks a lot for your replies. I tried the following and still to no avail.

Here are the results of the various commands:

# cat /proc/mdstat
Personalities :
md0 : inactive sda2[0](S) sdb1[4](S) sdc2[1](S)
      480215144 blocks super 1.2

unused devices: <none>

# mdadm -V
mdadm - v3.2.6 - 25th October 2012

# uname -a
Linux triveni 3.10.6-2-ARCH #1 SMP PREEMPT Tue Aug 13 09:47:01 CEST 2013
x86_64 GNU/Linux

# mdadm -Esv
ARRAY /dev/md/0  level=raid5 metadata=1.2 num-devices=4
UUID=01b153ea:a93c7325:c13bf9cf:3195666f name=sysresccd:0
   devices=/dev/sdc2,/dev/sdb1,/dev/sda2

Based on Roger's mail, set the kernel option
"md_mod.start_dirty_degraded=1":

# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-linux root=/dev/mapper/triveni--lvm--320gp3-root rw
md_mod.start_dirty_degraded=1

Still, I get:

# mdadm -Avfs
mdadm: looking for devices for /dev/md0
mdadm: no RAID superblock on /dev/dm-6
mdadm: no RAID superblock on /dev/dm-5
mdadm: no RAID superblock on /dev/dm-4
mdadm: no RAID superblock on /dev/dm-3
mdadm: no RAID superblock on /dev/dm-2
mdadm: no RAID superblock on /dev/dm-1
mdadm: no RAID superblock on /dev/dm-0
mdadm: /dev/sdc2 is busy - skipping
mdadm: no RAID superblock on /dev/sdc1
mdadm: no RAID superblock on /dev/sdc
mdadm: /dev/sdb1 is busy - skipping
mdadm: no RAID superblock on /dev/sdb
mdadm: no RAID superblock on /dev/sda3
mdadm: /dev/sda2 is busy - skipping
mdadm: no RAID superblock on /dev/sda1
mdadm: no RAID superblock on /dev/sda



On 21-Sep-13 1:44 PM, Roger Heflin wrote:
> cat /proc/mdstat
> 
> It is probably already partially assembled (and since no force not
> active--note there is a kernel optionmd_mod.start_dirty_degraded=1
> that will enable if the array can at least work ) so not operational,
> typically you can stop it and it will no longer show up in mdstat then
> you can do what you are trying to do.
> 
> lsof will not show things that are being held open/busy in the kernel,
> lsof only shows userspace useage.
> 
> On Sat, Sep 21, 2013 at 9:32 AM, Sachin Garg
> <sgarg.bugreporter@gmail.com> wrote:
>> Hi,
>>
>> I am on Arch Linux. I have a 4 device RAID 5 of which 1 device is no longer
>> working. I am unable to assemble the raid.
>>
>> The active devices are:/dev/sda2, /dev/sdb1, /dev/sdc2
>>
>> The errors I get are like:
>>
>> # mdadm -Avf /dev/md127
>> mdadm: looking for devices for /dev/md127
>> mdadm: no RAID superblock on /dev/dm-6
>> mdadm: no RAID superblock on /dev/dm-5
>> mdadm: no RAID superblock on /dev/dm-4
>> mdadm: no RAID superblock on /dev/dm-3
>> mdadm: no RAID superblock on /dev/dm-2
>> mdadm: no RAID superblock on /dev/dm-1
>> mdadm: no RAID superblock on /dev/dm-0
>> mdadm: /dev/sdc2 is busy - skipping
>> mdadm: no RAID superblock on /dev/sdc1
>> mdadm: no RAID superblock on /dev/sdc
>> mdadm: /dev/sdb1 is busy - skipping
>> mdadm: no RAID superblock on /dev/sdb
>> mdadm: no RAID superblock on /dev/sda3
>> mdadm: /dev/sda2 is busy - skipping
>> mdadm: no RAID superblock on /dev/sda1
>> mdadm: no RAID superblock on /dev/sda
>>
>> I would like to know what is making these devices busy. I do not see any
>> indication from lsof or from the device mapper that these devices are being
>> used. I have even changed the  initramfs and the fstab etc. to prevent this
>> array from being started at boot time - still unable to assemble it.
>>
>> This array contains my /home and I do not know how to recover it.
>>
>> Help please ...
>>
>> Thanks,
>> Sachin
>> --
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