Description of problem:

Installing Linux onto a degraded software RAID-1 volume should be permitted if the user really wants and needs to do it. This is a common situation when, for example, migrating from Windows Server where one of the mirrored drives is used for the new Linux installation and data files are copied from the remaining Windows Server drive before synchronizing the RAID and overwriting it.

Version-Release number of selected component (if applicable):

Fedora Server 23

How reproducible:

Perfectly reproducible.

Steps to Reproduce:

1. Manually partition a new disk (/dev/sda1) with MBR type 0xFD.

2. Create a new md device with 2 devices but 1 missing:

mdadm --create /dev/md0 --level=1 --raid-devices=2 --metadata=0.9 /dev/sda1 missing

3. Run the Fedora installer.

Actual results:

The RAID-1 volume (/dev/md0) shows up as "unknown" and cannot be used for installation.

Expected results:

Although a warning is certainly indicated, there should be some way to manually override this and get the installer to permit installing onto a degraded software RAID volume.

Additional info:

Debian supports this installation mode correctly.