Actually, I have mirrored a single drive without losing data.
The help file in RAIDXpert claims you can migrate a single drive RAID 0 to RAID 1. I think I went from either JBOD or RAID ready to a single drive RAID 0. Then from 0 to 1 (mirrored).
You are also supposed to be able to migrate from either RAID 0 or 1 to RAID 5 or 10.
I am using RAIDXpert Version: 3.3.1540.9, Build Date: May 13, 2011.
Note, if the BIOS and chipset do not support RAID 5, you can't create RAID 5 without using RAID software.
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Two: HD 4550, Phenom II x6 1090T on MSI 870A-G54, 16 GB DDR3 1333
Two: Asrock E350M1, 8 GB DDR3 1333
HD 5570, Athlon II X4 630 on Gigabyte GA-870A-UD3, 16 GB DDR3 1333
Dual HD 4650's in CrossfireX, on MSI RD 480 Neo2, 4GB DDR2 800.