raid-1 starting with 1 drive after brief hiatus with cruddy controller.

raid-1 starting with 1 drive after brief hiatus with cruddy controller.

[r23]

Hi all, I have (2) 4.6 TB drives in software Raid 1 
mdadm - v3.3.2  on debian jessie. A new controller
zapped something and I have reverted to the prior built in 
controller.  I think 1 of the 2 is salvagable but need
some help getting the array started with the 1 drive (sda2 )
that is responding with raid info. sda2 was the other
drive and does not respond to --examine.

I think i've boiled it down to this when trying to scan/run:

mdadm: failed to add /dev/sdb2 to /dev/md/debian:0: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md/debian:0: Invalid argument

Also not clear on if the name should be /dev/md0 or /dev/md/debian:0,
when I run scan/run with a name of /dev/md/debian:0 it ends up in the
/dev directory as /dev/md0

All the info follows.

I would like to get it started with the single drive / sda2 , 
in read-only mode to capture a backup.



root@mars:/home/user14# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0   4.6T  0 disk
-─sda1   8:1    0     1G  0 part
|-sda2   8:2    0   4.6T  0 part
sdb      8:16   0   4.6T  0 disk
-─sdb1   8:17   0     1G  0 part
|-sdb2   8:18   0   4.6T  0 part
sdc      8:32   0 149.1G  0 disk
-─sdc1   8:33   0  78.1G  0 part
-─sdc2   8:34   0     1K  0 part
-─sdc5   8:37   0  33.6G  0 part
-─sdc6   8:38   0  18.1G  0 part
|-sdc7   8:39   0  19.2G  0 part
sdd      8:48   0 232.9G  0 disk
-─sdd1   8:49   0   8.4G  0 part /
-─sdd2   8:50   0     1K  0 part
-─sdd5   8:53   0   2.8G  0 part
-─sdd6   8:54   0     4G  0 part [SWAP]
-─sdd7   8:55   0   380M  0 part
|-sdd8   8:56   0 217.4G  0 part /home
sr0     11:0    1  1024M  0 rom
sr1     11:1    1   7.8G  0 rom
root@mars:/home/user14#


root@mars:~/raid/bin# mdadm --misc --examine /dev/sda2
mdadm: No md superblock detected on /dev/sda2.


root@mars:~/raid/bin# mdadm --misc --examine /dev/sdb2
/dev/sdb2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 2a3489a6:b430c744:2c89a792:98521913
           Name : debian:0
  Creation Time : Sat May  9 17:44:25 2015
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 9765179392 (4656.40 GiB 4999.77 GB)
     Array Size : 4882589696 (4656.40 GiB 4999.77 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=0 sectors
          State : clean
    Device UUID : 4697b088:5d3b1ae5:55d30f65:516df63d

Internal Bitmap : 8 sectors from superblock
    Update Time : Wed Jun 14 23:53:27 2017
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : 1f245410 - expected 1f249410
         Events : 129099


   Device Role : Active device 1
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
root@mars:~/raid/bin# 


root@mars:~/raid/bin/util/lsdrv# ./lsdrv 
PCI [sata_via] 00:0f.0 IDE interface: VIA Technologies, Inc. VT8237A SATA 2-Port Controller (rev 80)
   scsi 0:0:0:0 ATA      TOSHIBA MD04ACA5 {75T8K3HXFS9A}
       sda 4.55t [8:0] Partitioned (gpt)
        sda1 1.00g [8:1] ext2 'skip_space' {b03b8699-d492-42b1-af9e-2a68b73b733d}
        sda2 4.55t [8:2] ext3 'for_raid' {5c93e223-8b7a-48b9-b4f0-6ef2990f22ae}
   scsi 1:0:0:0 ATA      TOSHIBA MD04ACA5 {84JHK4XKFS9A}
    sdb 4.55t [8:16] Partitioned (gpt)
     sdb1 1.00g [8:17] ext2 'fs_on_sdd1' {78546565-c92d-4008-b372-104c6337c11e}
     sdb2 4.55t [8:18] MD raid1 (2) inactive 'debian:0' {2a3489a6-b430-c744-2c89-a79298521913}
PCI [pata_via] 00:0f.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 07)
   scsi 2:0:0:0 PIONEER  DVD-RW  DVR-111D {PIONEER_DVD-RW_DVR-111D}
       sr0 1.00g [11:0] Empty/Unknown
   scsi 2:0:1:0 ATA      WDC WD1600JB-00G {WD-WCAL98126376}
       sdc 149.05g [8:32] Partitioned (dos)
        sdc1 78.13g [8:33] ntfs {72280E84280E4795}
        sdc2 1.00k [8:34] Partitioned (dos)
        sdc5 33.62g [8:37] vfat {04CA-B75D}
        sdc6 18.13g [8:38] ext2 'for_temp' {6cc1aa46-aaa3-4f93-8316-8924ac9ee3f2}
        sdc7 19.17g [8:39] ext4 'for_var' {8d865846-5827-4f51-b826-6f672d45285d}
   scsi 3:0:0:0 ATA      WDC WD2500JB-00G {WD-WCAL76218162}
    sdd 232.89g [8:48] Partitioned (dos)
     sdd1 8.38g [8:49] ext4 {7e42bfae-8af9-4c9a-b8c2-7e70c37435a1}
         Mounted as /dev/sdd1 @ /
     sdd2 1.00k [8:50] Partitioned (dos)
     sdd5 2.79g [8:53] ext4 {907474bc-cec7-4a80-afb0-daa963cef388}
     sdd6 3.99g [8:54] swap {cbe9107e-8503-4597-8f99-5121384dfd1b}
     sdd7 380.00m [8:55] ext4 {daf44546-1549-42be-b632-2be175962366}
     sdd8 217.34g [8:56] ext4 {9f3bfd18-92ac-4095-b512-cc2a0b88737c}
      Mounted as /dev/sdd8 @ /home
USB [usb-storage] Bus 002 Device 005: ID 0480:d010 Toshiba America Info. Systems, Inc.  {20121204025996}
   scsi 5:0:0:0 Toshiba  External USB 3.0 {66715465}
    sde 1.82t [8:64] Partitioned (dos)
     sde1 1.82t [8:65] ntfs 'ELLIS' {ACAC8FDBAC8F9E88}
      Mounted as /dev/sde1 @ /mnt/ellis
Other Block Devices
   md0 0.00k [9:0] MD v1.2  () clear, None (None) None {None}
                 Empty/Unknown
root@mars:~/raid/bin/util/lsdrv# 



root@mars:~/raid/bin/util/lsdrv# mdadm --manage --stop /dev/md0                  
mdadm: stopped /dev/md0

root@mars:~/raid/bin/util/lsdrv#  mdadm --assemble /dev/md/debian:0  -v /dev/sdb2 --run
mdadm: looking for devices for /dev/md/debian:0
mdadm: /dev/sdb2 is identified as a member of /dev/md/debian:0, slot 1.
mdadm: no uptodate device for slot 0 of /dev/md/debian:0
mdadm: failed to add /dev/sdb2 to /dev/md/debian:0: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md/debian:0: Invalid argument

root@mars:~/raid/bin/util/lsdrv# ls -lR /dev | grep md                                 
lrwxrwxrwx  1 root root            25 Jun 15 21:20 initctl -> /run/systemd/initctl/fifo
lrwxrwxrwx  1 root root            28 Jun 15 21:20 log -> /run/systemd/journal/dev-log
drwxr-xr-x  2 root root            40 Jun 15 17:20 md
brw-rw----  1 root disk        9,   0 Jun 17 21:54 md0
lrwxrwxrwx 1 root root 6 Jun 17 21:54 9:0 -> ../md0
/dev/md:

root@mars:~/raid/bin/util/lsdrv# mdadm --detail /dev/md0                               
/dev/md0:
        Version : 1.2
     Raid Level : raid0
  Total Devices : 0
    Persistence : Superblock is persistent

          State : inactive

    Number   Major   Minor   RaidDevice
root@mars:~/raid/bin/util/lsdrv# 
root@mars:~/raid/bin/util/lsdrv# 

root@mars:~/raid/bin/util/lsdrv# cat /proc/mdstat
Personalities : 
unused devices: <none>
root@mars:~/raid/bin/util/lsdrv# 

Re: raid-1 starting with 1 drive after brief hiatus with cruddy controller.

[Wols Lists]

On 18/06/17 05:14, r23@anchordrop.net wrote:
> Hi all, I have (2) 4.6 TB drives in software Raid 1 
> mdadm - v3.3.2  on debian jessie. A new controller
> zapped something and I have reverted to the prior built in 
> controller.  I think 1 of the 2 is salvagable but need
> some help getting the array started with the 1 drive (sda2 )
> that is responding with raid info. sda2 was the other
> drive and does not respond to --examine.
> 
> I think i've boiled it down to this when trying to scan/run:
> 
> mdadm: failed to add /dev/sdb2 to /dev/md/debian:0: Invalid argument
> mdadm: failed to RUN_ARRAY /dev/md/debian:0: Invalid argument
> 
> Also not clear on if the name should be /dev/md0 or /dev/md/debian:0,
> when I run scan/run with a name of /dev/md/debian:0 it ends up in the
> /dev directory as /dev/md0

Probably doesn't matter. Internally, mdadm is using /dev/md/debian:0 to
indicate (if I've got this right) that this is the first raid array
created on a machine called "debian". That's meant to protect you
against trashing arrays if you move drives between machines. I'm
guessing you've said "md0" in your commands trying to get the array to
run, so mdadm is also using md0 to refer to the array. It gets even more
confusing because once things start working again, it'll call it md127
in all probability :-) Long and short of it, don't worry about this.
> 
> All the info follows.
> 
> I would like to get it started with the single drive / sda2 , 
> in read-only mode to capture a backup.
> 
It appears from what you've mentioned below, that sda2 has had its
superblock trashed. In other words, you're not going to get that working
without some expert help. However, sdb2 is okay ...

Incidentally, have you been doing a "mdadm --stop /dev/md0" between
every one of your attempts to get things running? If you haven't, then
it's likely to have played havoc with your attempts, as a partially
assembled array usually refuses to do anything ...
> 
> 
> root@mars:/home/user14# lsblk
> NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
> sda      8:0    0   4.6T  0 disk
> -─sda1   8:1    0     1G  0 part
> |-sda2   8:2    0   4.6T  0 part
> sdb      8:16   0   4.6T  0 disk
> -─sdb1   8:17   0     1G  0 part
> |-sdb2   8:18   0   4.6T  0 part
> sdc      8:32   0 149.1G  0 disk
> -─sdc1   8:33   0  78.1G  0 part
> -─sdc2   8:34   0     1K  0 part
> -─sdc5   8:37   0  33.6G  0 part
> -─sdc6   8:38   0  18.1G  0 part
> |-sdc7   8:39   0  19.2G  0 part
> sdd      8:48   0 232.9G  0 disk
> -─sdd1   8:49   0   8.4G  0 part /
> -─sdd2   8:50   0     1K  0 part
> -─sdd5   8:53   0   2.8G  0 part
> -─sdd6   8:54   0     4G  0 part [SWAP]
> -─sdd7   8:55   0   380M  0 part
> |-sdd8   8:56   0 217.4G  0 part /home
> sr0     11:0    1  1024M  0 rom
> sr1     11:1    1   7.8G  0 rom
> root@mars:/home/user14#
> 
> 
> root@mars:~/raid/bin# mdadm --misc --examine /dev/sda2
> mdadm: No md superblock detected on /dev/sda2.
> 
This is what implies sda2 has somehow been trashed ... :-(
> 
> root@mars:~/raid/bin# mdadm --misc --examine /dev/sdb2
> /dev/sdb2:
>           Magic : a92b4efc
>         Version : 1.2
>     Feature Map : 0x1
>      Array UUID : 2a3489a6:b430c744:2c89a792:98521913
>            Name : debian:0
>   Creation Time : Sat May  9 17:44:25 2015
>      Raid Level : raid1
>    Raid Devices : 2
> 
>  Avail Dev Size : 9765179392 (4656.40 GiB 4999.77 GB)
>      Array Size : 4882589696 (4656.40 GiB 4999.77 GB)
>     Data Offset : 262144 sectors
>    Super Offset : 8 sectors
>    Unused Space : before=262056 sectors, after=0 sectors
>           State : clean
>     Device UUID : 4697b088:5d3b1ae5:55d30f65:516df63d
> 
> Internal Bitmap : 8 sectors from superblock
>     Update Time : Wed Jun 14 23:53:27 2017
>   Bad Block Log : 512 entries available at offset 72 sectors
>        Checksum : 1f245410 - expected 1f249410
>          Events : 129099
> 
> 
>    Device Role : Active device 1
>    Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
> root@mars:~/raid/bin# 
> 
This is a bit weird! An array state of AA indicates that the array is
okay! This is where I would have done a --detail on /dev/md0 or
/dev/md/debian:0
> 
> root@mars:~/raid/bin/util/lsdrv# ./lsdrv 
> PCI [sata_via] 00:0f.0 IDE interface: VIA Technologies, Inc. VT8237A SATA 2-Port Controller (rev 80)
>    scsi 0:0:0:0 ATA      TOSHIBA MD04ACA5 {75T8K3HXFS9A}
>        sda 4.55t [8:0] Partitioned (gpt)
>         sda1 1.00g [8:1] ext2 'skip_space' {b03b8699-d492-42b1-af9e-2a68b73b733d}
>         sda2 4.55t [8:2] ext3 'for_raid' {5c93e223-8b7a-48b9-b4f0-6ef2990f22ae}
>    scsi 1:0:0:0 ATA      TOSHIBA MD04ACA5 {84JHK4XKFS9A}
>     sdb 4.55t [8:16] Partitioned (gpt)
>      sdb1 1.00g [8:17] ext2 'fs_on_sdd1' {78546565-c92d-4008-b372-104c6337c11e}
>      sdb2 4.55t [8:18] MD raid1 (2) inactive 'debian:0' {2a3489a6-b430-c744-2c89-a79298521913}
> PCI [pata_via] 00:0f.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 07)
>    scsi 2:0:0:0 PIONEER  DVD-RW  DVR-111D {PIONEER_DVD-RW_DVR-111D}
>        sr0 1.00g [11:0] Empty/Unknown
>    scsi 2:0:1:0 ATA      WDC WD1600JB-00G {WD-WCAL98126376}
>        sdc 149.05g [8:32] Partitioned (dos)
>         sdc1 78.13g [8:33] ntfs {72280E84280E4795}
>         sdc2 1.00k [8:34] Partitioned (dos)
>         sdc5 33.62g [8:37] vfat {04CA-B75D}
>         sdc6 18.13g [8:38] ext2 'for_temp' {6cc1aa46-aaa3-4f93-8316-8924ac9ee3f2}
>         sdc7 19.17g [8:39] ext4 'for_var' {8d865846-5827-4f51-b826-6f672d45285d}
>    scsi 3:0:0:0 ATA      WDC WD2500JB-00G {WD-WCAL76218162}
>     sdd 232.89g [8:48] Partitioned (dos)
>      sdd1 8.38g [8:49] ext4 {7e42bfae-8af9-4c9a-b8c2-7e70c37435a1}
>          Mounted as /dev/sdd1 @ /
>      sdd2 1.00k [8:50] Partitioned (dos)
>      sdd5 2.79g [8:53] ext4 {907474bc-cec7-4a80-afb0-daa963cef388}
>      sdd6 3.99g [8:54] swap {cbe9107e-8503-4597-8f99-5121384dfd1b}
>      sdd7 380.00m [8:55] ext4 {daf44546-1549-42be-b632-2be175962366}
>      sdd8 217.34g [8:56] ext4 {9f3bfd18-92ac-4095-b512-cc2a0b88737c}
>       Mounted as /dev/sdd8 @ /home
> USB [usb-storage] Bus 002 Device 005: ID 0480:d010 Toshiba America Info. Systems, Inc.  {20121204025996}
>    scsi 5:0:0:0 Toshiba  External USB 3.0 {66715465}
>     sde 1.82t [8:64] Partitioned (dos)
>      sde1 1.82t [8:65] ntfs 'ELLIS' {ACAC8FDBAC8F9E88}
>       Mounted as /dev/sde1 @ /mnt/ellis
> Other Block Devices
>    md0 0.00k [9:0] MD v1.2  () clear, None (None) None {None}
>                  Empty/Unknown
> root@mars:~/raid/bin/util/lsdrv# 
> 
It looks to me like somebody's created an ext3 partition on sda2, and
thereby trashed the raid ...
> 
> 
> root@mars:~/raid/bin/util/lsdrv# mdadm --manage --stop /dev/md0                  
> mdadm: stopped /dev/md0
> 
> root@mars:~/raid/bin/util/lsdrv#  mdadm --assemble /dev/md/debian:0  -v /dev/sdb2 --run
> mdadm: looking for devices for /dev/md/debian:0
> mdadm: /dev/sdb2 is identified as a member of /dev/md/debian:0, slot 1.
> mdadm: no uptodate device for slot 0 of /dev/md/debian:0
> mdadm: failed to add /dev/sdb2 to /dev/md/debian:0: Invalid argument
> mdadm: failed to RUN_ARRAY /dev/md/debian:0: Invalid argument
> 
> root@mars:~/raid/bin/util/lsdrv# ls -lR /dev | grep md                                 
> lrwxrwxrwx  1 root root            25 Jun 15 21:20 initctl -> /run/systemd/initctl/fifo
> lrwxrwxrwx  1 root root            28 Jun 15 21:20 log -> /run/systemd/journal/dev-log
> drwxr-xr-x  2 root root            40 Jun 15 17:20 md
> brw-rw----  1 root disk        9,   0 Jun 17 21:54 md0
> lrwxrwxrwx 1 root root 6 Jun 17 21:54 9:0 -> ../md0
> /dev/md:
> 
> root@mars:~/raid/bin/util/lsdrv# mdadm --detail /dev/md0                               
> /dev/md0:
>         Version : 1.2
>      Raid Level : raid0
>   Total Devices : 0
>     Persistence : Superblock is persistent
> 
>           State : inactive
> 
>     Number   Major   Minor   RaidDevice
> root@mars:~/raid/bin/util/lsdrv# 
> root@mars:~/raid/bin/util/lsdrv# 
> 
> root@mars:~/raid/bin/util/lsdrv# cat /proc/mdstat
> Personalities : 
> unused devices: <none>
> root@mars:~/raid/bin/util/lsdrv# 
> 
Hmmm. I don't want to suggest too much, but the array is expecting two
devices, so saying just "/dev/sdb2" is probably its invalid argument.
Try changing that to "/dev/sdb2 missing".

And if that improves matters but the array won't run, you might want to
"--readonly --force". But I'd wait for someone else to chime in that
this is a good idea before trying this.

Hope this has given you some ideas.
Cheers,
Wol

Re: raid-1 starting with 1 drive after brief hiatus with cruddy controller.

[r23]

I have 2 scenarios here:

scenario 1- I tried the argument 'missing'. I think its taking that as a literal device name. I'm
probably not doing it like your asking.

root@mars:~# 
root@mars:~# mdadm --manage --stop /dev/md0              
mdadm: error opening /dev/md0: No such file or directory
root@mars:~# ls -lR /dev | grep md
lrwxrwxrwx  1 root root            25 Jun 18 11:52 initctl -> /run/systemd/initctl/fifo
lrwxrwxrwx  1 root root            28 Jun 18 11:52 log -> /run/systemd/journal/dev-log
drwxr-xr-x  2 root root            40 Jun 18 07:52 md
/dev/md:
root@mars:~#  mdadm --assemble /dev/md/debian:0  -v --run /dev/sdb2 missing
mdadm: looking for devices for /dev/md/debian:0
mdadm: cannot open device missing: No such file or directory
mdadm: missing has no superblock - assembly aborted
root@mars:~#


Scenario 2: - trying to explicitly add the good disk:

1) examine /dev/sdb2 
2)  mdadm --assemble /dev/md/md0  -v --run /dev/sdb2  : result = failed to add /dev/sdb2 to /dev/md/md0: Invalid argument
3) mdadm --manage /dev/md0 -v --add  /dev/sdb2 : result  =  mdadm: Cannot get array info for /dev/md0
4) mdadm --detail -v /dev/md0  = result = raid0 ??

detail on above 4 steps:

root@mars:~# 
root@mars:~# mdadm --misc --examine /dev/sdb2
/dev/sdb2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 2a3489a6:b430c744:2c89a792:98521913
           Name : debian:0
  Creation Time : Sat May  9 17:44:25 2015
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 9765179392 (4656.40 GiB 4999.77 GB)
     Array Size : 4882589696 (4656.40 GiB 4999.77 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=0 sectors
          State : clean
    Device UUID : 4697b088:5d3b1ae5:55d30f65:516df63d

Internal Bitmap : 8 sectors from superblock
    Update Time : Wed Jun 14 23:53:27 2017
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : 1f245410 - expected 1f249410
         Events : 129099


   Device Role : Active device 1
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
root@mars:~# mdadm --assemble /dev/md/md0  -v --run /dev/sdb2
mdadm: looking for devices for /dev/md/md0
mdadm: /dev/sdb2 is identified as a member of /dev/md/md0, slot 1.
mdadm: no uptodate device for slot 0 of /dev/md/md0
mdadm: failed to add /dev/sdb2 to /dev/md/md0: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md/md0: Invalid argument
root@mars:~# ls -lR /dev | grep md
lrwxrwxrwx  1 root root            25 Jun 18 11:52 initctl -> /run/systemd/initctl/fifo
lrwxrwxrwx  1 root root            28 Jun 18 11:52 log -> /run/systemd/journal/dev-log
drwxr-xr-x  2 root root            40 Jun 18 07:52 md
brw-rw----  1 root disk        9,   0 Jun 18 11:57 md0
lrwxrwxrwx 1 root root 6 Jun 18 11:57 9:0 -> ../md0
/dev/md:
root@mars:~# mdadm --manage /dev/md0 -v --add  /dev/sdb2
mdadm: Cannot get array info for /dev/md0
root@mars:~# mdadm --detail -v /dev/md0
/dev/md0:
        Version : 1.2
     Raid Level : raid0
  Total Devices : 0
    Persistence : Superblock is persistent

          State : inactive

    Number   Major   Minor   RaidDevice
root@mars:~# 

Re: raid-1 starting with 1 drive after brief hiatus with cruddy controller.

[NeilBrown]

[-- Attachment #1: Type: text/plain, Size: 1745 bytes --]

On Sun, Jun 18 2017, r23@anchordrop.net wrote:
>
> root@mars:~/raid/bin# mdadm --misc --examine /dev/sdb2
> /dev/sdb2:
>           Magic : a92b4efc
>         Version : 1.2
>     Feature Map : 0x1
>      Array UUID : 2a3489a6:b430c744:2c89a792:98521913
>            Name : debian:0
>   Creation Time : Sat May  9 17:44:25 2015
>      Raid Level : raid1
>    Raid Devices : 2
>
>  Avail Dev Size : 9765179392 (4656.40 GiB 4999.77 GB)
>      Array Size : 4882589696 (4656.40 GiB 4999.77 GB)
>     Data Offset : 262144 sectors
>    Super Offset : 8 sectors
>    Unused Space : before=262056 sectors, after=0 sectors
>           State : clean
>     Device UUID : 4697b088:5d3b1ae5:55d30f65:516df63d
>
> Internal Bitmap : 8 sectors from superblock
>     Update Time : Wed Jun 14 23:53:27 2017
>   Bad Block Log : 512 entries available at offset 72 sectors
>        Checksum : 1f245410 - expected 1f249410

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

checksum is wrong.

> root@mars:~/raid/bin/util/lsdrv#  mdadm --assemble /dev/md/debian:0  -v /dev/sdb2 --run
> mdadm: looking for devices for /dev/md/debian:0
> mdadm: /dev/sdb2 is identified as a member of /dev/md/debian:0, slot 1.
> mdadm: no uptodate device for slot 0 of /dev/md/debian:0
> mdadm: failed to add /dev/sdb2 to /dev/md/debian:0: Invalid argument

Bad checksum caused kernel to reject the device.

There is no obvious way to correct the checksum, but I think you can
force it by using the --update option to --assemble
e.g.

  mdadm --assemble /dev/md/debian:0 --update=name -v /dev/sdb2

When doing that, you should check that other fields all look correct
first, because something must have changed to affect the bitmap.
(I cannot see anything that looks wrong)

NeilBrown

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]

Re: raid-1 starting with 1 drive after brief hiatus with cruddy controller.

[NeilBrown]

[-- Attachment #1: Type: text/plain, Size: 281 bytes --]

On Sun, Jun 18 2017, Wols Lists wrote:

> Hmmm. I don't want to suggest too much, but the array is expecting two
> devices, so saying just "/dev/sdb2" is probably its invalid argument.
> Try changing that to "/dev/sdb2 missing".

"missing" is only relevant for --create

NeilBrown

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]

Re: raid-1 starting with 1 drive after brief hiatus with cruddy controller.

[r23]

Hi All,

mdadm --assemble /dev/md/debian:0 --update=name -v /dev/sdb2 --run

started the container with the 1 drive and I was able to mount it !!

Thank you all very much. Happy day :)

root@mars:~/raid/bin/util#  mdadm --assemble /dev/md/debian:0 --update=name -v /dev/sdb2 --run
mdadm: looking for devices for /dev/md/debian:0
mdadm: /dev/sdb2 is identified as a member of /dev/md/debian:0, slot 1.
mdadm: no uptodate device for slot 0 of /dev/md/debian:0
mdadm: added /dev/sdb2 to /dev/md/debian:0 as 1
mdadm: /dev/md/debian:0 has been started with 1 drive (out of 2).
root@mars:~/raid/bin/util# mkdir /mnt/thanks
root@mars:~/raid/bin/util# mount -o ro /dev/md/debian:0 /mnt/thanks
root@mars:~/raid/bin/util# cd /mnt/thanks
root@mars:/mnt/thanks# ls -l
total 63900
drwxr-xr-x 19 root   userme     4096 Nov  7....
::
::
::
----------------

On Mon, 19 Jun 2017 06:59:18 +1000
NeilBrown <neilb@suse.com> wrote:

> On Sun, Jun 18 2017, r23@anchordrop.net wrote:
> >
> > root@mars:~/raid/bin# mdadm --misc --examine /dev/sdb2
> > /dev/sdb2:
> >           Magic : a92b4efc
> >         Version : 1.2
> >     Feature Map : 0x1
> >      Array UUID : 2a3489a6:b430c744:2c89a792:98521913
> >            Name : debian:0
> >   Creation Time : Sat May  9 17:44:25 2015
> >      Raid Level : raid1
> >    Raid Devices : 2
> >
> >  Avail Dev Size : 9765179392 (4656.40 GiB 4999.77 GB)
> >      Array Size : 4882589696 (4656.40 GiB 4999.77 GB)
> >     Data Offset : 262144 sectors
> >    Super Offset : 8 sectors
> >    Unused Space : before=262056 sectors, after=0 sectors
> >           State : clean
> >     Device UUID : 4697b088:5d3b1ae5:55d30f65:516df63d
> >
> > Internal Bitmap : 8 sectors from superblock
> >     Update Time : Wed Jun 14 23:53:27 2017
> >   Bad Block Log : 512 entries available at offset 72 sectors
> >        Checksum : 1f245410 - expected 1f249410
> 
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> checksum is wrong.
> 
> > root@mars:~/raid/bin/util/lsdrv#  mdadm
> > --assemble /dev/md/debian:0  -v /dev/sdb2 --run mdadm: looking for
> > devices for /dev/md/debian:0 mdadm: /dev/sdb2 is identified as a
> > member of /dev/md/debian:0, slot 1. mdadm: no uptodate device for
> > slot 0 of /dev/md/debian:0 mdadm: failed to add /dev/sdb2
> > to /dev/md/debian:0: Invalid argument
> 
> Bad checksum caused kernel to reject the device.
> 
> There is no obvious way to correct the checksum, but I think you can
> force it by using the --update option to --assemble
> e.g.
> 
>   mdadm --assemble /dev/md/debian:0 --update=name -v /dev/sdb2
> 
> When doing that, you should check that other fields all look correct
> first, because something must have changed to affect the bitmap.
> (I cannot see anything that looks wrong)
> 
> NeilBrown