NVME: AHCI or RAID?

[ashic]

Hello,
I've just got a Dell Precision 5510 with a single m.2 NVME SSD. It won't have a second hard drive, as I've gone for extra battery. The BIOS has a section for SATA configuration, with the following options:

* Disabled
* AHCI
* RAID

I've heard somewhere that NVME drives benefit from Intel's RAID controller, and the default Win 7 install was on RAID. I'm wiping it and putting Windows 10 and potentially Ubuntu on there.

My question is - will the RAID option give any benefits? Or should I choose AHCI and avoid driver hassles?

 

[Elixer]

AHCI.
Don't bother with RAID on a one drive system.

 

[ashic]

Thanks for the response.

The "raid" is essentially Intel Rapid Storage Technology (RST). Apparently the RST results in faster performance, though the bit I'm fuzzy about is that the RST drivers are used for both AHCI and "raid" during a windows install. Does that mean I'd get the same performance with AHCI and "raid"?

 

[Zodiark1593]

For some reason my mobo defaulted my SSD to RAID. I did try changing to AHCI but blue-screened upon boot, but it works on the RAID setting, so whatever.

edit: Using Win 7 btw.

 

[ashic]

Windows would be ok with the formware Raid, it's getting linux to see it that's a problem. Usually if you install Windows on Raid, AHCI or ATA (disabled), and change to another, it'll blue screen.

On further digging, it seems the only benefit the "raid" setting gives is various multi disk options, and for single disk, it uses AHCI. Which is what AHCI does anyway. As such, I went with AHCI. Windows installed with additional driver, and ubuntu sees the drive oob (though until some better linux drivers are out, going linux host seems impossible).

 

[bradly1101]

I believe AHCI/RAID is only effective on the SATA port(s), not on PCIe-connected m.2 slots for NVMe drives, but I could be wrong.

 

[ashic]

The AHCI/Raid options are under SATA operation, however I can confirm that OOB, Ubuntu 15.10 can see the drive under AHCI, but not under RAID. (Another weird thing is that the BIOS gives you the option to wipe all internal data on next boot, but that only covers non PCIE drives.) BIOSes aren't exactly great UX or terminology

 

[Zodiark1593]

Windows would be ok with the formware Raid, it's getting linux to see it that's a problem. Usually if you install Windows on Raid, AHCI or ATA (disabled), and change to another, it'll blue screen.

Considering I'm several months in this install, I'm not planning on reinstalling the OS and everything else just to fix what apparently seems to be working (and still saturating SATA 3 at that).

From what I understand, AHCI is derived from RAID, or something to that effect. I'm not aware of any disadvantages of running in that mode for a single drive nor have I experienced any myself. If AHCI is working for your needs, use it.

I haven't messed with any m.2 drives, though I would assume there's a separate option for PCI-e drives as they don't use SATA. Perhaps the BIOS defaults it to NVME if you use it as the boot drive.

 

[McLovin]

When using the m.2 slot, if the drive is NVMe it will stritcly use the PCIe bus and won't touch the SATA controller but you will have to use the NVMe driver from either Samsung or Intel depending on the manufacturer. You will also need to do your windows install in UEFI mode and not BIOS/Legacy mode (The drive will also have to be formatted with GPT and not MBR, but I don't believe you can do MBR when in UEFI mode anyway). If the drive is m.2 SATA then you use AHCI for single configuration and RAID if you have multiple drivers (or you use Intel Rapid Start Technology, but I haven't messed with it because I still haven't seen SSD handled any type of sleep mode very well). You should not have to use UEFI mode in order to use m.2 SATA drives.


Intel NVMe Driver (Standalone driver for use during Windows Install): http://www.smartredirect.de/redir/c...5-Recommended-AHCI-RAID-and-NVMe-Drivers.html

Samsung NVMe Driver (Standalone driver for use during Windows Install): http://www.smartredirect.de/redir/c...5-Recommended-AHCI-RAID-and-NVMe-Drivers.html

If you are using Windows 7, you will not see your NVMe drive during setup unless you add the above drivers during the install. You can also slipstream the KB from Microsoft that will add generic NVMe support, but honestly sticking in a USB thumb drive and telling windows to get the NVMe driver off of the drive seems way less time consuming than slipstreaming the KB in. I believe this is the same procedure for Windows 8, but I haven't used or installed Windows 8 or 8.1 so YMMV.

If you install Windows 10 my understanding is that 10 supports NVMe natively so you can get through the install without having to add drivers but I have not installed Windows 10 so again, YMMV.

 

[Phynaz]

The AHCI/Raid options are under SATA operation, however I can confirm that OOB, Ubuntu 15.10 can see the drive under AHCI, but not under RAID. (Another weird thing is that the BIOS gives you the option to wipe all internal data on next boot, but that only covers non PCIE drives.) BIOSes aren't exactly great UX or terminology

This is weird, RAID is a superset of AHCI, therefore if it works under AHCI it should certainly work under RAID.

 

[Phynaz]

AHCI.
Don't bother with RAID on a one drive system.

There's no reason to not select RAID, as it is a superset of AHCI.