How to install software raid 0 on ubuntu 12.04 server with mdadm?

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http://askubuntu.com – I need to install a software raid-0 array on a Ubuntu 12.04 server with mdadm through commandline (SSH). The drive setup is as follows: SDA = OS SSD SDB = HDD for raid 0 SDC = HDD for raid 0 (HowTos)