Hello, I did work out that mdadm in d-i uses a config file of /tmp/mdadm.conf instead of the usual /etc/mdadm/mdadm.conf.
I thought this meant that if I put the things I needed into that file then that would work out. Unfortunately I see that any time you go into mdcfg it clobbers any existing /tmp/mdadm.conf: https://salsa.debian.org/installer-team/mdcfg/-/blob/master/mdcfg.sh#L443 So, I guess you could do it by switching to another virtual console as soon as you enter mdcfg and make your config change then. In my case I was on a serial console so didn't have any virtual consoles to switch to. I could still do it by loading the netconsole component and SSH'ing in. At that point though I may as well create all the MD arrays entirely by hand in the d-i shell, which is what I was trying to avoid. I don't see an easy way of having d-i's mdadm respect a config file of my choice, unless I have missed something. Cheers, Andy
