Registry values for msachi and iaStorV "Start" variable

[Lord Method Man]

Right now my values for both

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
and
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\iaStorV

Start variables are set to "3"

My system configuration consists of:

Main HDD (Windows): Single SSD on SATA_0
Secondary HDD: 2 disks in RAID 0 on SATA_1 and SATA_2

Since I'm using onboard RAID 0 for my secondary drive, the BIOS is set to RAID mode.

I've read that for AHCI "Start" in msachi should be 0, but I havent found definitive instructions for RAID mode in BIOS. I am not getting AHCI type functions (safely remove option, etc) with these drives currently.

Can anyone with a similar setup explain what these values mean and what they should be set at? Motherboard is a Gigabyte 970A-UD3 and I am running Windows 7 64-bit.

 

[Lord Method Man]

I had thought that RAID was a superset of AHCI, but with my BIOS set to RAID mode I don't get the options I was used to with previous systems using AHCI such as the option to safely remove my SATA drives and policy options for Quick Removal.

 

[essenbe]

Here is a tutorial to change to AHCI mode

 

[Lord Method Man]

Thanks, what I'm wondering about is since my BIOS is set to RAID rather than AHCI mode, which of the two values (iaStorV or msachi) should be changed to "0"

 

[logicearth]

If your two drives are in RAID 0 you do not want the ability to hot swap them.

 

[Lord Method Man]

I have more drives in the system than just the 2 in RAID 0, including an eSATA enclosure that connects to another of the motherboard's SATA ports via a rear bracket adapter.

 

[essenbe]

I have alsways changed both values to 0, no matter which I was really using. Go to device manager and expand IDE ATA/ATAPI controllers and see what driver(s) are listed at the bottom. IaStor is Intel's AHCI driver, but it comes from their IRST package (Raid package).

 

[Lord Method Man]

There is no IDE ATA/ATAPI controllers section in the Device Manager of this particular system like there usually is in my other builds. I just have "AMD ACHI Compatible RAID Controller" listed under Strorage controllers instead.

 

[essenbe]

OK, that makes sense. If you change that, I'm sure it will break your raid. I have never run raid, but I believe if you change your storage configuration in bios from raid to AHCI, it will break your raid. But, I would also think your non raid drives are in AHCI mode. If you would like to see, download As SSD Benchmark, open it and select your SSD. You don't have to run the test, just post a screenshot of the As SSD window with your SSD selected.

 

[Lord Method Man]

Oh I definitely can't change my BIOS from RAID. I'm only looking to change Windows registry values so I can have the option to safely remove my eSATA drives. As I said I thought AHCI was a subset of RAID. I think I'm just going to set the msachi value and see what happens.

 

[essenbe]

MSAHCI is Microsoft's ahci controller, You are using AMD's raid.ahci controller. I'm relatively sure your non raid drives are using AMD's AHCI controller from the raid controller.

 

[Lord Method Man]

Well, my old system used AMD 770 chipset and was set to AHCI in BIOS, Windows defaulted to msachi 0 and iaStorV 3.