Re: Can't mount /dev/md0 Raid5

[Joseba Ibarra <wajalotnet@gmail.com>]

Hi Mikael,

I had ext4

and for commands:

root@grafico:/mnt# fsck -n /dev/md0
fsck de util-linux 2.29.2
e2fsck 1.43.4 (31-Jan-2017)
ext2fs_open2(): Bad magic number in superblock
fsck.ext2: invalid superblock, trying backup blocks...
fsck.ext2: Bad magic number in super-block while trying to open /dev/md0

The superblock could not be read or does not describe a ext2/ext3/ext4 
filesystem.
If the device is invalid and it really contains an ext2/ext3/ext4 filesystem
(and not swap or ufs or something else), then the superblock is corrupt; 
and you might try running e2fsck with an alternate superblock:
     e2fsck -b 8193 <device>
  o
     e2fsck -b 32768 <device>

A gpt partition table is found in /dev/md0


I'm getting more escared....... No idea what to do

Thanks
> Mikael Abrahamsson <mailto:swmike@swm.pp.se>
> 11 de octubre de 2017, 16:01
> On Wed, 11 Oct 2017, Joseba Ibarra wrote:
>
>
> Do you know what file system you had? Looks like next step is to try 
> to run fsck -n (read-only) on md0 and/or md0p1.
>
> What does /etc/fstab contain regarding md0?
>
> Joseba Ibarra <mailto:wajalotnet@gmail.com>
> 11 de octubre de 2017, 13:56
> Hi Adam
>
> root@grafico:/mnt# cat /proc/mdstat
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
> [raid4] [raid10]
> md0 : inactive sdd1[3] sdb1[1] sdc1[2]
>       2929889280 blocks super 1.2
>
> unused devices: <none>
>
>
> root@grafico:/mnt# mdadm --manage /dev/md0 --stop
> mdadm: stopped /dev/md0
>
>
> root@grafico:/mnt# mdadm --assemble /dev/md0 /dev/sd[bcd]1
> mdadm: /dev/md0 assembled from 3 drives - not enough to start the 
> array while not clean - consider --force.
>
>
>
> root@grafico:/mnt# cat /proc/mdstat
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
> [raid4] [raid10]
> unused devices: <none>
>
> At this point I´ve followed the advise using --force
>
> root@grafico:/mnt# mdadm --assemble --force /dev/md0 /dev/sd[bcd]1
> mdadm: Marking array /dev/md0 as 'clean'
> mdadm: /dev/md0 has been started with 3 drives (out of 4).
>
>
> root@grafico:/mnt# cat /proc/mdstat
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
> [raid4] [raid10]
> md0 : active (auto-read-only) raid5 sdb1[1] sdd1[3] sdc1[2]
>       2929889280 blocks super 1.2 level 5, 512k chunk, algorithm 2 
> [4/3] [_UUU]
>       bitmap: 0/8 pages [0KB], 65536KB chunk
>
> unused devices: <none>
>
>
> Now I see the RAID, however can't be mounted. So, I'm not sure how to 
> backup the data. Gparted shows the partition /dev/md0p1 with the used 
> and free space.
>
>
> If I try
>
> mount /dev/md0 /mnt
>
> again the output is
>
> mount: wrong file system, bad option, bad superblock in /dev/md0, 
> missing codepage or helper program, or other error
>
>     In some cases useful info is found in syslog - try dmesg | tail or 
> something like that.
>
> I do dmesg | tail
>
> If I try root@grafico:/mnt# mount /dev/md0p1 /mnt
> mount: /dev/md0p1: can't read superblock
>
> And
>
>
> root@grafico:/mnt# dmesg | tail
> [ 3263.411724] VFS: Dirty inode writeback failed for block device 
> md0p1 (err=-5).
> [ 3280.486813]  md0: p1
> [ 3280.514024]  md0: p1
> [ 3452.496811] UDF-fs: warning (device md0): udf_fill_super: No 
> partition found (2)
> [ 3463.731052] JBD2: Invalid checksum recovering block 630194476 in log
> [ 3464.933960] Buffer I/O error on dev md0p1, logical block 630194474, 
> lost async page write
> [ 3464.933971] Buffer I/O error on dev md0p1, logical block 630194475, 
> lost async page write
> [ 3465.928066] JBD2: recovery failed
> [ 3465.928070] EXT4-fs (md0p1): error loading journal
> [ 3465.936852] VFS: Dirty inode writeback failed for block device 
> md0p1 (err=-5).
>
>
> Thanks a lot for your time
>
>
> Joseba Ibarra
>
> Adam Goryachev <mailto:adam@websitemanagers.com.au>
> 11 de octubre de 2017, 13:29
> Hi Rudy,
>
> Please send the output of all of the following commands:
>
> cat /proc/mdstat
>
> mdadm --manage /dev/md0 --stop
>
> mdadm --assemble /dev/md0 /dev/sd[bcd]1
>
> cat /proc/mdstat
>
> mdadm --manage /dev/md0 --run
>
> mdadm --manage /dev/md0 --readwrite
>
> cat /proc/mdstat
>
>
> Basically the above is just looking at what the system has done 
> currently, stopping/clearing that, and then trying to assemble it 
> again, finally, we try to start it, even if it has one faulty disk.
>
> At this stage, chances look good for recovering all your data, though 
> I would advise to get yourself a replacement disk for the dead one so 
> that you can restore redundancy as soon as possible.
>
> Regards,Adam
>
>
>
>
>
> Joseba Ibarra <mailto:wajalotnet@gmail.com>
> 11 de octubre de 2017, 13:14
> Hi Rudy
>
> 1- Yes, with all 4 disk plugged in, system does not boot
> 2- Yes, with the broken disk unplugged, it boots
> 3 - Yes, raid does not assemble during boot. I assemble manually doing
>
> root@grafico:/home/jose# mdadm --assemble --scan /dev/md0
> root@grafico:/home/jose# mdadm --assemble --scan
> root@grafico:/home/jose# mdadm --assemble /dev/md0
>
> 4 -When I try to mount
>
>   mount /dev/md0 /mnt
>
> mount: wrong file system, bad option, bad superblock in /dev/md0, 
> missing codepage or helper program, or other error
>
>     In some cases useful info is found in syslog - try dmesg | tail or 
> something like that.
>
> I do dmesg | tail
>
> root@grafico:/mnt# dmesg | tail
> [  705.021959] md: pers->run() failed ...
> [  849.719439] EXT4-fs (md0): unable to read superblock
> [  849.719564] EXT4-fs (md0): unable to read superblock
> [  849.719589] EXT4-fs (md0): unable to read superblock
> [  849.719616] UDF-fs: error (device md0): udf_read_tagged: read 
> failed, block=256, location=256
> [  849.719625] UDF-fs: error (device md0): udf_read_tagged: read 
> failed, block=512, location=512
> [  849.719638] UDF-fs: error (device md0): udf_read_tagged: read 
> failed, block=256, location=256
> [  849.719642] UDF-fs: error (device md0): udf_read_tagged: read 
> failed, block=512, location=512
> [  849.719643] UDF-fs: warning (device md0): udf_fill_super: No 
> partition found (1)
> [  849.719667] isofs_fill_super: bread failed, dev=md0, iso_blknum=16, 
> block=32
>
> Thanks a lot for your helping
> Rudy Zijlstra <mailto:rudy@grumpydevil.homelinux.org>
> 11 de octubre de 2017, 12:42
> Hi Joseba,
>
>
>
> Let me see if i understand you correctly
>
> - with all 4 disks plugged in, your system does not boot
> - with the broken disk unplugged, it boots (and from your description 
> it is really broken, no DISK recovery possible unless by specialised 
> company)
> - raid does not get assembled during boot, you do a manual assembly?
>      -> please provide the command you are using
>
> from the log above, you should be able to do a mount of /dev/md0 which 
> would auto-start the raid.
>
> If that works, the next step would be to check the health of the other 
> disks. smartctl would be your friend.
> Another useful action would be to copy all important data to a backup 
> before you add a new disk to replace the failed disk.
>
> Cheers
>
> Rudy

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