How to mount a Raid1 disk originating from a different system

[ozotto]

@malcolmlewis

Since your not showing ALL information, it’s hard to surmize, small steps are needed…

I did show you all info step by step … nothing hidden

some additional info might be interesting

localhost:/ # mdadm -X /dev/md/0_0
mdadm: This is an md array.  To view a bitmap you need to examine
mdadm: a member device, not the array.
mdadm: Reporting bitmap that would be used if this array were used
mdadm: as a member of some other array
        Filename : /dev/md/0_0
           Magic : 00000000
mdadm: invalid bitmap magic 0x0, the bitmap file appears
mdadm: to be corrupted or missing.
         Version : 0
mdadm: unknown bitmap version 0, either the bitmap file
mdadm: is corrupted or you need to upgrade your tools

localhost:/ # mdadm -E /dev/md/0_0
mdadm: No md superblock detected on /dev/md/0_0.
localhost:/ #

Why am i referring to /dev/md/0_0 and not /dev/127 because md/0_0 is listed in the partition overview. /dev/127 only shows up

localhost:/ # cat /proc/mdstat
Personalities : [raid1] 
**md127** : active (read-only) raid1 sdc2[1]
      955287040 blocks super 1.0 [2/1] [_U]
      bitmap: 7/8 pages [28KB], 65536KB chunk

md0 : active raid1 sdb1[1]
      468859712 blocks super 1.0 [2/1] [_U]
      bitmap: 4/4 pages [16KB], 65536KB chunk

unused devices: <none>
localhost:/ # 

At one point in time, before I put the problem up in the forum, I made a wrong turn (embarrassing), so to speak.

… what to do ?

…anyway Happy NewYear

[malcolmlewis]

@ozotto yup, so it’s mount /dev/md127 /mnt

[ozotto]

@malcolmlewis

localhost:/ # cat /proc/mdstat
Personalities : [raid1] 
md127 : active (read-only) raid1 sdc2[1]
      955287040 blocks super 1.0 [2/1] [_U]
      bitmap: 7/8 pages [28KB], 65536KB chunk

md0 : active raid1 sdb1[1]
      468859712 blocks super 1.0 [2/1] [_U]
      bitmap: 4/4 pages [16KB], 65536KB chunk

unused devices: <none>

localhost:/ # mount /dev/md127 /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/md127, missing codepage or helper program, or other error.
       dmesg(1) may have more information after failed mount system call.
localhost:/ # 

It says it is active ??

[malcolmlewis]

@ozotto What about mdadm -D /dev/md127 output?

[malcolmlewis]

@ozotto So I have a couple of RAID1 NVMe’s here that I plugged into a USB adaptor;

cat /proc/mdstat
Personalities : [raid1] 
md126 : active raid1 sdd2[0]
      120839104 blocks [2/1] [U_]
      bitmap: 1/1 pages [4KB], 65536KB chunk

mount /dev/md126p1 /mnt

ls /mnt
bin  boot  data  dev  etc  extra  home  lib  lib64  mnt  opt  proc  root  run  sbin  .snapshots  srv  stuff  sys  tmp  usr  var

lsblk -f /dev/sdd
NAME          FSTYPE            FSVER  LABEL     UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sdd                                                                                                  
├─sdd1        vfat              FAT32  ESP       D7F4-EB9C                                           
└─sdd2        linux_raid_member 0.90.0           d5c1abe3-c3f5-7245-2bac-d447d9b033ee                
  └─md126                                                                                            
    └─md126p1 btrfs                    LP103125E 8db7816d-2e86-4606-8173-2009533747f7   90.7G    20% /mnt

You might need to specify the type in the assemble command --metadata=1.0

[ozotto]

@malcolmlewis
Hi Malcolm , thank you for your help. I need to come back to it at a later date.
I have some other issues (software) which need to be addressed more urgently.

Again happy new year to you and your team

greetings from “Down Under”