I've tried mv and rename it doesn't work.

Yes, I'm just trying to stop mdadm from reporting it's findings at boot time:-

Can't rm it because mdadm may have a signature on the HDD which could cause other issues.

I'll see what the Live CD does when I can.

"doesn't work" is not diagnostically helpful (although frequently indicates user error).

What does that even mean?

If you have no mdadm arrays, you have no need for mdadm.
What does show (may need to install aptitude).

-:::-With or without elevated privileges trying to rename the mdadm.conf file does not work-:::-
The file show's no change what so ever:-

Even tho a Raid Array is not set up there may still be a signature (related to mdadm/raid setup) that is associated with Raid attached to the HDD that Debian 9 is installed on.

Why not show us?There may also be leprechauns under your bed... shamrock patterned pyjamas should ward them off

When attempting to rename the file I get the error message shown in post # 25.

lol

As per my post #30, that is just incorrect usage of 'rename'.
Just use a simple 'mv' (as root b/c it's a system file).

Or, better than monkeying around moving stuff that your system is expecting to be there - just remove the package.

1 members found this post helpful.

I'm using mv correctly but not rename correctly.

Renaming those files with mv worked now to rename the mdadm.conf file shouldn't be that difficult.
I'll try again:-

Renaming that configuration file worked:-

However; I'm still getting this error at boot time:
Are you sure removing mdadm won't wreck the system?

As I mentioned, my Debian Testing runs fine without mdadm installed. If for whatever reason it don't boot or run properly, you can always reinstall it from a chroot or single user mode if it and it's dependencies are in /var/cache/apt/archives.

I looked here:
https://wiki.debian.org/chroot

Never used chroot before Brains.

Suggestions?

Is this MBR partition scheme (Legacy BIOS) or GPT partitions (UEFI)?

1 members found this post helpful.

MBR:-

You can do this two ways:
The first may not give internet access, but you can boot the Debian installer media and select Advanced/Rescue mode from the menu. It will go through many of the install questions but eventually ask which partition you want to mount, it should list a few since you have 3 drives, but you'll want to mount the Debian root partition, next you would select to go to a terminal inside the selected root partition where you can then install mdadm. But if it and it's dependencies are not in the cache, and there is no internet, it won't be able to retrieve necessary packages from the mirrors configured in /etc/apt/sources.list.

The other option is to boot a live (Preferably Debian derivative) CD, you should hopefully still have Mint. Mint has great support for network devices, you would open a terminal and issue the commands below to go into a chroot and reinstall mdadm, the "xxxx" would need be replaced with appropriate device such as /dev/sda1, needs to be the Debian root partition:
You may need to use sudo for the first three and last two commands if using Mint

But it's highly unlikely you'll need to reinstall mdadm. When you go to uninstall mdadm, it'll show before confirming what all other packages will need be uninstalled. In my earlier posts, I show which packages are dependencies of mdadm, if there are other packages that will need be uninstalled, means mdadm was installed as a dependency for these other packages, at which time you can decide if you want to go ahead. It's possible the other packages are also not needed as they may simply have been installed as a "Suggested" or "Recommended" package, which are not actually needed to keep the system running properly, they are just bloatware.

Sorry, I've been doing lots of fruit and vegetables lately.

You can do the chroot thing from the Mint that's installed, no need for Live CD.