A few days ago, I was installing a Fedora 18 on a brand-new machine, which had two 1TB SATA hard drives which I wanted to put into a RAID1 (mirroring) configuration. mdadm makes managing software RAID on Linux easy, and the Fedora Installer (anaconda) has always had extremely powerful tools for setting up a RAID.

Anaconda also supports Logical Volume Manager (LVM), which is part of the recommended configuration for Fedora, because it adds lots of cool features, like being able to have non-contiguous partitions, moving partitions around the disk, between disks, and even spanning disks!

Combining the data redundant of mdadm with the partitioning features of LVM is a common strategy, but unfortunately one that's not longer supported in Fedora 18's Anaconda. In fact, there's an open bug on the subject, and a very heated discussion on the mailing lists.

The official solution is to forego the graphical installer entirely, and is to use a kickstart script -- Anaconda's automated install mode. After a lot of trial and error, I managed to get a kickstart that works, but only when the installer was booted with noefi. The kickstart was copied onto a FAT32-formatted flash drive as the file ks.cfg, and loaded with the boot parameter ks=hd:/sdc1/ks.cfg

This kickstart has one down side: it formats the entire raw disks, so it's not suitable for adding a Fedora installation to an existing LVM-with-mdadm configuration. I'm still investigating how to get anaconda to cooperate when the RAID and LVM is already configured.