You may access your RAID detail status via GUI:

1) Open disk utility in terminal and look for RAID Array. Depending on the version of the Ubuntu Server installed, the command might be varied:

  • Ubuntu 12.04 LTS: palimpsest
  • Ubuntu 14.04.02 LTS: gnome-disks

2) Open the disk utility from your application menu:

  • Ubuntu 12.04 LTS: Accessories > Disk Utility
  • Ubuntu 14.04.02 LTS: Settings > Disks

For advanced users, if you already know your RAID device name, then you can simply type the following command in terminal:

sudo mdadm --detail /dev/md1

* assuming /dev/md1 is your RAID device name

To know your RAID device name, run this command in terminal: cat /proc/mdstat. The name appears before the colon (:).