Originally posted by: Astrallite
XP mode cannot detect drives that are under AHCI. Vista can. Pretty gay.
This is very misleading. XP has no included drivers for AHCI, sure, but it is a fairly straightforward process to add them. Granted, it's getting harder due to lack of floppy drives in a lot of systems...
Originally posted by: Satsuki
"Intel recommends choosing RAID mode on their motherboards (which also enables AHCI) rather than the plain AHCI/SATA mode for maximum flexibility, due to the issues caused when the mode is switched once an operating system has already been installed."
I first installed Windows XP on a 250GB HD in SATA mode. I then installed Windows 7 on two 500GB HDs (RAID 0) in RAID mode.
I can't detect my 250GB in 7, but I can in the BIOS. Is this due to switching modes? Do SATA/RAID controllers only support one configuration at a time?
Could someone give me general non-super-technical information about AHCI? I hear it allows SATA to use NCQ and hot-plugging. Anything else?
I have a AHCI mode, what's the difference between RAID and AHCI modes? I know enabling RAID will automatically enable AHCI.
AHCI is a protocol, like a language. The AHCI SATA mode and the AHCI RAID mode of your motherboard are two different modes that each speak the same language. Sure they speak the same language, but that doesn't mean if you use AHCI RAID mode that it works exactly the same as AHCI SATA mode. For the sake of understanding, I think it's easier to think of AHCI mode and RAID mode as mutually exclusive, even though they share a common protocol.
When in AHCI mode, you need an AHCI driver (not included by default in XP, but included in Vista). You do have additional capabilities over IDE (sometimes called Legacy) mode like hot-swap support and NCQ. The controller allows direct access to any device it can see.
When in RAID mode, you need the Intel Matrix RAID driver (not included by default in XP, and I'm not positive about Vista). You have the same additional capabilities as AHCI like hot-swap and NCQ. You also have the added RAID support. This controller does not allow direct access to any device, but rather transforms the physical disks into logical RAID volumes. In order to access your storage, you must create RAID volumes, and those RAID volumes are exported to the operating system for access.
I think the reason that you're not seeing your 250GB disk with XP on it is that the RAID controller sees the disk, but it is not part of a RAID volume so the operating system doesn't get to see it. Creating a RAID volume on the disk will likely destroy your data. You should try to connect it via a different SATA controller or maybe an external USB enclosure if you need access.