Setup email notifications for mdadm (with a bit of Ruby)

It can be useful to receive mdadm email alerts as otherwise you may not know about issues with your RAID until it’s too late. These instructions for setting up the alerts are adapted from this post.

mdadm expects a local mail server (e.g. postfix) to be configured to send emails. My preference, however, was to use GMail’s SMTP server, as I didn’t want to figure out how to configure postfix.

I wrote a simple Ruby script to send out emails:

require 'net/smtp'

to = "******"
from = '******'
password = '******'
msg = "Net/SMTP email from Ruby"

smtp = "", 587
smtp.start(Socket.gethostname, from, password, 'plain' ) { |smtp|  
  smtp.open_message_stream(from, [to]) do |f|
    f.puts "From: #{from}"
    f.puts "To: #{to}"
    f.puts "Subject: #{ARGV[1]}"
    f.puts ARGV[0]  

It accepts the text of the message and the subject as command line arguments.

Here is how I configured mdadm to use it:

  • put the script into /usr/sbin/email.rb and make sure it’s executable
  • add this line to /etc/mdadm/mdadm.conf:
    PROGRAM /usr/sbin/email.rb

This will send you a message with the RAID device name in the subject.

To test that it’s working:

  • edit /etc/default/mdadm and add --test to the end of the DAEMON_OPTIONS string
  • restart mdadm with sudo service mdadm restart and you should receive an email
  • remove --test from /etc/default/mdadm and restart mdadm again.

One more thing to note that the first real notification you are likely to receive will be about a rebuild, which can be confusing. This is caused by a monthly (read-only) redundancy check of the array. More details here.

Works with: Ubuntu 9.10, mdadm