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Windows 7: Switching SATA Mode from RAID to AHCI

16 May 2013   #1
azhe

Windows 7 Home Premium x64 SP1
 
 
Switching SATA Mode from RAID to AHCI

While dealing with another issue, I've been told that I should switch my SATA mode from RAID to AHCI. I do not have a RAID array and don't plan to. However, I've been told that I would need drivers for this, and I'm not sure if my Windows installation has them or not. I don't want to switch modes only to boot Windows and have it corrupted or god-knows-what. So could someone tell me if it's possible to just switch? Or should I check for drivers first?


My System SpecsSystem Spec
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16 May 2013   #2
TwoCables

 

First of all, is it really currently set to RAID mode in the BIOS?
My System SpecsSystem Spec
17 May 2013   #3
TVeblen

Microsoft Community Contributor Award Recipient

Windows 7 64 Bit Home Premium SP1
 
 

Your Windows installation has them, but they must be activated.

The procedure is really no different than changing from IDE mode to AHCI: you edit the Registry to activate AHCI driver, reboot and go directly into the BIOS, change the SATA mode to AHCI, and then start back into windows. But there is one extra step.

Change from IDE here:
AHCI : Enable in Windows 7 / Vista

Change from RAID here (scroll down to "let me fix it myself")
Error message occurs after you change the SATA mode of the boot drive
Note that you may need to change the IastorV key to 0 instead of msahci.

Note that it says you must change ONE of the values to 0. That should be Msahci. IastorV is Windows RAID driver.
My System SpecsSystem Spec
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17 May 2013   #4
azhe

Windows 7 Home Premium x64 SP1
 
 

Quote   Quote: Originally Posted by TwoCables View Post
First of all, is it really currently set to RAID mode in the BIOS?
In BIOS I see Storage->Storage Options->SATA Emulation, set to RAID. So I assume so. Furthermore I've seen messages on my computer regarding RAID (which I do not use).

Quote   Quote: Originally Posted by TVeblen View Post
Change from RAID here (scroll down to "let me fix it myself")
Error message occurs after you change the SATA mode of the boot drive
Note that you may need to change the IastorV key to 0 instead of msahci.
I did as the article said, and each time it bluescreens on boot. I tried enabling msahci, then vice versa, and it doesn't work. It will still only boot in RAID mode.

Is there another step I missed? All I did was edit the registry, then change the mode in BIOS. Is there something else that needs to be done to enable them?

I don't know if a memory dump was created from the crashes, but if it would help I could post them if you could tell me where to find them.
My System SpecsSystem Spec
17 May 2013   #5
azhe

Windows 7 Home Premium x64 SP1
 
 

I apologize if double-posting is bad, but I have more information that might help. I'll edit my post from now on if that's what I should do.

Would Windows fail to boot (as it did) if the drive had some kind of RAID metadata on it? I just ran a command (sudo dmraid -r) in Linux that gives me this:
Code:
/dev/sda: pdc, "pdc_bbhjjee", stripe, ok, 1953124992 sectors, data@ 0
sda is my Windows drive, the drive that shipped with this PC. HP advertised it as "RAID Ready," even though it didn't come with a RAID.

I'm pretty sure it's possible for me to remove this data via Linux, but would that cause any harm to my Windows installation? I don't want to do it if I can't boot to Windows afterwards.
My System SpecsSystem Spec
17 May 2013   #6
TwoCables

 

I'm not sure, but I know that the values for the subkeys below all have to be 0:
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\msahci
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\iaStorV
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\iaStor
My System SpecsSystem Spec
17 May 2013   #7
azhe

Windows 7 Home Premium x64 SP1
 
 

I removed the RAID metadata on the drive and it works fine. So that is not the problem.
Quote   Quote: Originally Posted by TwoCables View Post
I'm not sure, but I know that the values for the subkeys below all have to be 0:
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\msahci
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\iaStorV
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\iaStor
Setting either or both msahci and iaStorV to 0 results in a bluescreen after switching to AHCI mode. I do not have a iaStor key. Seeing as my other problem has been solved in spite of this, would it be okay to leave this as is? Or is very important that it be in AHCI mode?
My System SpecsSystem Spec
17 May 2013   #8
bassfisher6522

Windows 7 Ultimate 64 bit
 
 

Is the PC you talking about the same one listed in your "My System Specs"? If so, then I should think that the factory settings for it would be optimized as far as drive modes go. Unless you added another drive to the system or an SSD and needed to change the drive modes, the SATA mode should be the default setting and should be just fine.

Otherwise, in order to switch to RAID mode or AHCI mode, those drivers must be installed and enabled before the OS is installed otherwise you will get those BSOD's and a reinstall of the OS is required. Basically, the AHCI mode is needed if you're going to install a HDD greater then 2TB or an SSD. IDE mode, is basically for legacy drives

I've not used TVelben's suggestions on editing the registry and rebooting. Nice find btw TVelben, I've only installed the drivers, enabled it in the BIOS and the set boot order for cd/dvd, reboot then format and clean installed.
My System SpecsSystem Spec
17 May 2013   #9
TVeblen

Microsoft Community Contributor Award Recipient

Windows 7 64 Bit Home Premium SP1
 
 

I too have always set AHCI first and then installed Windows. I only had to change from IDE mode once on a repair. And the process went off without a hitch. I have never tried it from RAID mode. I can't image why it won't work.

Perhaps the driver files are not included in an HP customized install (except, why would they do that?)

Bottom line: if it ain't broke don't fix it. The RAID driver is very often the same as the AHCI driver anyway (not always, but common - I've seen a few download sites that only offered an AHCI/RAID driver, not one or the other). So if everything is working as it should then you could just leave it.

Why are you being told you need to change it?
My System SpecsSystem Spec
17 May 2013   #10
essenbe

Windows 7 Enterprise X64/Windows 10 Enterprise X64/Windows 10 Pro X64/Linux Mint
 
 

The OP has an AMD CPU so would not have an IaStor setting. IaStor is Intel's AHCI driver. If he is set up in raid mode, his installation is striped. If he actually is running raid, his only option is to reinstall in AHCI mode. A screenshot of disk management should tell whether he is in a striped array. Disk Management - Post a Screen Capture Image
But, as TVeblen said above. If it is in raid and running OK and there is no compelling reason he needs to change, let it stay the way it is. If the time comes to reinstall, he can change it then.
My System SpecsSystem Spec
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