“root account locked” after removing one RAID1 hard disc

[c.buhtz@posteo.jp]

X-Post: https://serverfault.com/q/1044339/374973

I tried this out in a VirtualMachine to hope I can learn something.

**Problem**

The RAID1 does not containt any systmem relevant data - the OS is on 
another drive. My Debian 10 does not boot anymore and tells me that I am 
in emergency mode and "Cannot open access to console, the root account 
is locked.". I removed one of the two RAID1 devices before.

And systemd tells me while booting "A start job is running for 
/dev/md127".

**Details***

The virtual machine contains three hard disks. /dev/sda1 use the full 
size of the disc and containts the Debian 10. /dev/sdb and /dev/sdc (as 
discs without partitions) are configured as RAID1 /dev/md127 and 
formated with ext4 and mounted to /Daten. I can read and write without 
any problems to the RAID.

I regualr shutdown and then removed /dev/sdc. After that the system does 
not boot anymore and shows me the error about the locked root account.

**Question 1**

Why is the system so sensible about one RAID device that does not 
contain essential data for the boot process. I would I understand if 
there is a error messages somewhere. But blocking the whole boot process 
is to much in my understanding.

**Question 2**

I read that a single RAID1 device (the second is missing) can be 
accessed without any problems. How can I do that?

**More details**

Here is the output of my fdisk -l. Interesting here is that /dv/md127 is 
shown but without its filesysxtem.

> Disk /dev/sda: 128 GiB, 137438953472 bytes, 268435456 sectors
> Disk model: VBOX HARDDISK
> Disklabel type: dos
> Disk identifier: 0xe3add51d
> 
> Device     Boot Start       End   Sectors  Size Id Type
> /dev/sda1  *     2048 266338303 266336256  127G 83 Linux
> 
> 
> Disk /dev/sdb: 8 GiB, 8589934592 bytes, 16777216 sectors
> Disk model: VBOX HARDDISK
> 
> Disk /dev/sdc: 8 GiB, 8589934592 bytes, 16777216 sectors
> Disk model: VBOX HARDDISK
> 
> Disk /dev/md127: 8 GiB, 8580497408 bytes, 16758784 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes

Here is mount output:

> sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
> /dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro)
> /dev/md127 on /Daten type ext4 (rw,relatime)

This is /etc/fstab:

> # <file system> <mount point>   <type>  <options>       <dump>  <pass>
> # / was on /dev/sda1 during installation
> UUID=65ec95df-f83f-454e-b7bd-7008d8055d23 /               ext4    
> errors=remount-ro 0       1
> 
> /dev/md127  /Daten      ext4    defaults    0   0