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from what I understand performance is more important when you hit raid 5, 6, 50, 60 and other kinds that are more sophisticated algorithms than mirrored or striped.
Raid 5 involves calculating parity and writing it someplace else than the data itself.
 
I'm looking at setting up a new RAID set now. Firstly, SoftRAID's driver is now included with MacOS, so you should be able to read a set of SoftRAID disks, at least, with no additional software. Also, SoftRAID offer a free version which can read drives and swap disks from your existing sets.

You get 30 days trial of the Pro level product, so that's enough to create your set.
 
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