Traditionally, booting an Ubuntu installation with the root filesystem on a degraded RAID drops the system into a busybox prompt in the initramfs.
This is a very conservative approach, allowing the system administrator to consciously recognize that the system has lost a RAID disk, and preventing the system from booting into an unprotected situation.
This can be problematic on Ubuntu server machines which are expected to boot unattended. Some administrators may wish to configure a system to boot automatically, even if in a degraded state. We have recently added support for this to Intrepid's mdadm and initramfs-tools packages.
A system administrator can now statically configure this in Intrepid with:
echo "BOOT_DEGRADED=true" | sudo tee -a /etc/initramfs-tools/conf.d/mdadm
Additionally, this can be specified (overridden, actually) on the kernel boot line with the
More details on this specification, and full instructions on how you can help test this functionality can be found in the wiki at: