As far as I’m concerned the decision by the Ubuntu Team to default to failing to boot when a raid array is degrade is a complete mistake. When your decision is the opposite of what everyone else has chosen to do in a given situation, you’re probably doing it wrong. Having an option for people to choose to fail to boot on a degraded array is a great idea and one that would probably almost never be used. But I’m all for options, and also for sensible defaults. So on any Ubuntu system where you’re running mdadm raid don’t forget to do either:
sudo dpkg-reconfigure mdadm
- update /etc/initramfs-tools/conf.d/mdadm and set BOOT_DEGRADED=true
sudo update-initramfs -u -k all
Every Ubuntu system with mdadm RAID, every time.