Comment 29 for bug 361689

I think I can get you started.

I mean, the first step to creating a RAID volume is to think it out. Where do you need redundancy? Where do you need speed? Then map out your partitions (especially if you have different sized disks).

Remember that RAID will cause a slight (in the case of RAID0 or RAID1) to slightly greater (RAID5 or RAID6) processor and I/O load. That is the trade-off for getting better overall disk performance.

Although it is supposedly not needed to RAID0 your swap partitions across disks (supposedly the swap daemon manages multiple disks very well) it doesn't hurt to do so and is an easy and safe way to get started with RAID. You might consider making this your test case.

This page lays out mdadm and Linux RAID pretty well: http://ubuntuforums.org/showthread.php?t=408461

Basically:
1. format disks you want to use as "RAID" partitions
2. create a RAID array using "mdadm --create /dev/md0 --level=[level] --raid-devices=[number of devices] [device1] [device2]...[deviceN]
3. assemble the array
4. format the array in the filesystem of your choice (like any other partition)
5. mount it like you would any other disk partition

Pretty simple, eh?