[Hardcider] xServe software raid

[Lee Fickenscher]

I'm hoping to pick some brains that may have dealt with this before.
I added a second drive to my xserve and I want to mirror the single  
original drive using software raid.
The system is headless so I have to use the CLI to do this.
The manual has a blurb:
"To create an unpaired mirrored RAID from a single file system disk:
	$ diskutil enableRAID mirror device"
where mirror is the "Name of the mirror RAID set" and device is the  
device file.
Is this the command I want?
Do I need to create the RAID set first?
thanks,
Lee