For some reason md0 comes out of boot with four drives (should be five) and with inactive state.

I have 'ARRAY /dev/md0 UUID=15b5e460:b43a2510:2ce552e4:6d63ea58' line in mdadm.conf

But doing 'mdadm -A /dev/md0 after, works.

So why it do not do it on boot?

journalctl -b | grep 'mdadm' : do not give any output. So im little lost, how to even troubleshoot this.