Facter.add(:mdarrays) do
    confine :kernel => :linux
    setcode do
        arrays = []
        mdstat = "/proc/mdstat"
        if File.exists?(mdstat)
            File.readlines(mdstat).each do |line|
                if m = line.match(/^md[0-9]+/)
                    arrays << m[0]
                end
            end
        end
        arrays.sort.join(',')
    end
end