This is the second part of my posts on using RAID1 on Ubuntu 14.04, if you missed the first part see it here Installing Ubuntu 14.04 on RAID 1 and LVM
So your shiny RAID1 array lost a disk. DO NOT PANIC.
I’ll say that again, as you probably missed it in your panic.
DO NOT PANIC.
So you want an Ubuntu server machine running with RAID1 for reliability and LVM for flexibility.
TIP: Play around with this on a virtual machine.
It only takes 10 minutes for a new install.
I used a virtualbox guest. I created a test machine: 2CPUs, 2048MB RAM, 2 x 25Gb Hard disk.