archlinux with RAID install error Failed to connect to lvmetad. Falling back to device scanning.

to install grub with raid you need to trick some files before boot...

if using intel platform follow as said in guide

$ edit /etc/mkinitcpio.conf
 change:
BINARIES=(mdmon)
add
HOOKS=(base udev block mdadm filesystems)

save file and run:

$ mkinitcpio -p linux
make sure mdadm in hooks was added, when generating should see output (line above)

run grub-mkconfig -o /boot/grub/grub.cfg (when you get the error above)

If get error warning: failed to connect to lvmetad. falling back to device scanning. raid
instructions
leave chroot /mnt

$ mkdir /mnt/hostlvm
$ mount --bind /run/lvm /mnt/hostlvm
$ arch-chroot /mnt
$ ln -s /hostlvm /run/lvm

-- alternativa --
mkdir /mnt/hostrun
mount --bind /run /mnt/hostrun

Then, we chroot into the guest, and mount our host's /run/lvm in the guest's /run

arch-chroot /mnt
mkdir /run/lvm
mount --bind /hostrun/lvm /run/lvm


rerun grub-mkconfig -o /boot/grub/grub.cfg (when you get the error above)