Re: problem with mdadm FAI 6.2

First, check if /dev/md1 is already mounted.
Maybe the FAI boot process (using dracut inside the initrd) detect
this raid and activates it.

You may add a hook which wipes add signature of a soft raid using a
simple script. For e.g. under https://fai-project.org/download/misc/
there are partition.WIPEDISKS and wipe-all

These can also remove the disk partition label.
-- 
regards Thomas