How to boot centos 7 from software raid?

Question

Hard disks

Good day, gentlemen.
the question is.
there is a backup of centos 7. in the form of tar czvf backup.tar.gz /
there is a live cd of centos 7. 2 screws in the server.
breaking screws. 1 partition of 370GB. mark as fd (linux raid autodetect)
build raid
mdadm --create --level 1 /dev/md0 --raid-devices=2 --metadata=0.90 /dev/sda1 /dev/sdb1
everything is going, everything is fine.
format
mkfs.ext4 /dev/md0
mount
/mount /dev/md0 /mnt/cnt
unpack the archive there.
mount the necessary partitions.
mount --bind /dev/ /mnt/cnt/dev/
mount --bind /proc/ /mnt/cnt/proc/
mount --bind /sys/ /mnt/cnt/sys/
and login
chroot /mnt/cnt/ /bin/bash is
where the questions start.
I rewrote fstab (wrote both UUID and /dev/md0)
mdadm --detail --scan > /etc/mdadm.conf
mv initramfs-3.10.0-229.7.2.rt56.141.6.el7.centos.x86_64.img initramfs -3.10.0-229.7.2.rt56.141.6.el7.centos.x86_64.img.baq
dracut /boot/initramfs-3.10.0-229.7.2.rt56.141.6.el7.centos.x86_64.img
then grub2- mkconfig -o /boot/grub2/grub.conf
this is how it sees it:
menuentry 'CentOS Linux 7 (Core), with Linux 3.10.0-229.el7.x86_64' --class rhel fedora --class gnu-linux - -class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-229.el7.x86_64-advanced-1059f673-bc2c-457a-b40c-19ef73554bfc' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod diskfilter
insmod mdraid09
insmod ext2
set root='mduuid/a2e6f8dbfff8a57904894333532a878b'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint='mduuid/a2e6f8dbfff8a57904894333532a878b' 1059f673-bc2c-457a-b40c-19ef73554bfc
else
search --no-floppy --fs-uuid --set =root 1059f673-bc2c-457a-b40c-19ef73554bfc
fi
linux16 /boot/vmlinuz-3.10.0-229.el7.x86_64 root=UUID=1059f673-bc2c-457a-b40c-19ef73554bfc ro crashkernel=auto rhgb0
initrd16 /boot/initramfs-3.10.0-229.el7.x86_64.img
} It
looks like the MD module should be loaded.
then I install the bootloader on both screws
grub2-install --recheck /dev/sda
grub2-install --recheck /dev/sdb
also tried writing to grub rd.auto=1 or rd.md.uuid=UUID which mdadm issues.
but after all these manipulations, I get that they say I can’t boot, /dev/disk/by-uuid/ does not exist. and throws it into the dracut rescue.
how to fix?

Answer 1

the solution is the following.
at the moment where dracut generates initramfs - generate on the stock kernel with the obligatory indication of the kernel, i.e. :
dracut /boot/initramfs-$(uname -r).img $(uname -r)
get bogged down in it and rebuild the normal rt kernel from there.

Answer 2

The easy way.
boot-repair-disk-64bit.iso
was googled. make a LiveCD.

Answer 3

I have another question, have you tried making more partitions in raid 1, more than three. When I reboot, it marks two partitions as inactive and falls out into the emergence mod. Failed to win.