Changing from RAID to AHCI

Question

Hi,

on my Dell E6510 I have my disk drive set to RAID mode. I have issues using the eSata port so I want to switch to AHCI. I followed the instructions here:http://support.microsoft.com/kb/922976. However when I boot my system after setting the disk mode to AHCI in the BIOS I see the Windows logo (using Win7 x64) and some seconds later I get a bluescreen with a message I can't read because the system is rebooting. Changing the BIOS back to RAID brings up the system again...

Anything I can do to make AHCI working?

Thanks,

---

Thomas Pagel

Answer 1

Hi Thomas,

Thank you for your post.

I believe I have the solution to your problem and I verified it against a Dell machine that has similar controller with your machine. Changing from AHCI to RAID,http://support.microsoft.com/kb/922976 fix will work.  

Changing from RAID to AHCI, you need one more step. Msahci driver requires Atapi.sys miniport to be loaded during boot as well. So you need to change theStart value to 0 for both of the following entries in your registry. You can use regedit.exe utility. 

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\msahci

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\atapi

Or you can also simply run the below command lines in an elevated window.

REG ADD HKLM\System\CurrentControlSet\Services\msahci /v Start /d 0 /f /t REG_DWORDREG ADD HKLM\System\CurrentControlSet\Services\atapi /v Start /d 0 /f /t REG_DWORD

Regards

Answer 2

Hi Thomas,

Richard has the right idea about your problem. Windows may be using different storage drivers for RAID and AHCI modes. Windows will try to load the RAID driver but the driver will not match the AHCI mode and bugcheck with famous 0x7B (INACCESSIBLE_BOOT_DEVICE). Startup repair will not work because it will not know which driver to load.

The easiest way is to reinstall the OS with AHCI mode.

Going back to the core problem, what issues are you seeing using the eSata port in RAID mode? 

PS:When changing SATA Mode, BIOS should warn you, saying something like "Attention! SATA mode changing may prevent the present operating system from booting or require a reinstall".

Thanks

Answer 3

My DELL Precision 7520 came preinstalled with Windows 10 having the boot disk, a NVMe M2 flash drive configured in RAID mode. I needed to change that to plain AHCI in order to be able to use tools that boot from their own USB stick like the disinfec't project from the German c't magazine as it would not recognize the orginal boot disk at all while in RAID mode.

This site was among the first I looked up for help. Unfortunately, the advice given here did not help, because Win10 didn't have the msahci registry entry anymore. Further findings told me that there is now IastorV instead of msahci, and that there is also a new entry storahci. Furthermore they suggested to lookup the StartOverride subkey of these service entries and to set the entry named "0" to the value "0". Summary: none of these helped.

What actually helped was a surprisingly simple: change the BIOS setting, boot into safe mode, and Windows 10 will automatically update all required settings. Then boot into normal mode again and you're done. This is described in detail here: https://www.tenforums.com/drivers-hardware/15006-attn-ssd-owners-enabling-ahci-mode-after-windows-10-installation.html

Answer 4

Hi,

My guess is that when you are changing to AHCI you are also "disassembling" the RAID.

RAID is an array of multiple disks connected to your SATA ports.

SATA ports have two flavors in BIOS: native IDE and AHCI, being the latest the most advanced one.

You should switch to AHCI in BIOS, but at the same time maintain the RAID structure.

Please read your motherboard manual very carefully on how to set up a RAID array with SATA AHCI interface.

You have now a RAID array configured with SATA "native" interface.

Carlos

Answer 5

你太英俊潇洒了 宝贝！可惜你很有可能看不懂中文，非常感谢！问题终于解决了。