MDADM RAID1 Home Server System disk error: incrementally starting raid arrays mdadm: Create user root not found

Solution 1:

I just had this problem too. I noticed that your md is numbered md126 which is usually a random number made up at boot time, not the number from mdadm.conf

In /boot/grub/grub.cfg, various things refer to both /dev/md?? and UUID=.....

Both are needed. If the machine is booting up with a random md??? number every time, initrd will struggle to find the raid and go in an endless loop.

I had to change these numbers because I re-created my md device.

update-grub grabs the md? number from what's currently running in /proc/mdstats and puts it into /boot/grub/grub.cfg

update-initramfs grabs the md? number from the /etc/mdadm/mdadm.conf file and puts it into /boot/initrd___ Both have to match.

When you boot via a rescue disk, /dev/md... is just whatever random number the rescue disk makes up. This is different to the md... number in /etc/mdadm/mdadm.conf

What I did was run mdadm --stop /dev/md... on all the disks. Then ran...

mdadm --assemble --config=/etc/mdadm/mdadm.conf --run
cat /proc/mdstat   # To check that the numbers are correct.
update-grub

If you needed to change /etc/mdadm/mdadm.conf, also run update-initramfs

Looks like your fstab says / was on /dev/md1 during installation; that's the number that may be in /boot/grub/grub.cfg and /etc/mdadm/mdadm.conf.