This article is part of System Recovery Week, examining techniques used to perform maintenance or recovery on a Fedora system in special circumstances.
When you boot from a Fedora installation disc and enter rescue mode, you have the option of having the filesystems from your Fedora installation mounted at /mnt/sysimage. If you do not select this option, or if it fails, RAID devices will not be configured for use (as is also the case with LVM, as discussed yesterday).
On a Fedora system, RAID arrays are managed by the mdadm utility. This program expects the RAID configuration to be available at /etc/mdadm.conf. In order to use mdadm without this configuration file, it is necessary to create a dummy configuration file. This is a multi-step process:
Create a dummy mdadm configuration file containing only the partitions to be scanned for possible RAID elements: