I should revise my explanation here:
I can have 4 disks in DOS (c:, d:, e:, and f:) and then turn on the RAID1 mode and there is just one disk c: only. If that is RAID0 then the c: must be 4-formatted first. That doesn't use any drivers or software except plain DOS.
The 4 disks would actually be RAID0+1 or RAID0 not just RAID1. I went back and edited poorly. I tested using one SATA disk and one PATA disk in RAID1 mode. The SATA disk was drive f: and the PATA disk was drive g: in DOS. Then I turned on the mirroring and there was only a drive f: and the mirroring worked. I could turn off the RAID1 and check each disk in DOS. There were no special drivers for the SATA or the RAID1. I am extrapolating to the same effect using 4 disks. I could only find one SATA disk in Linux and never see the PATA whether RAID was turned on or off because of the sata_promise driver for kernel 2.6.10. I could not write to the RAID in Linux without errors. The new 2.6.11 kernel is supposed to make the PATA visible under Linux. I haven't tested that yet. editor@postscript.port5.com --AMD Athlon64 @2.4Ghz Corsair TwinX1024-3200XL @480Mhz DDR ASUS A8V Deluxe ASUS Radeon A9250Ge/Td/256 Creative SB Live WD Raptor SATA Maxtor PATA IBM/Okidata Color PostScript3 Lexmark Mono PostScript2 Debian GNU/Linux debian-amd64/pure64 sid Kernel 2.6.11 XFree86 4.3.0.1 Xorg X11R6.8.2 1.5 Mb DSL