Last reply by 04-19-2021 Unsolved
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Why RAID with a SIngle Drive


I have a Dell Inspiron 7791 with 512gb pci & 32gb Optane, and Windows 10 Pro.

I have 2 questions:

1.The machine was set up with RAID. I don't understand why. How does RAID work with a single drive?

I will want to add a SATA SSD in the near future, and I do not want to be using RAID.

2. In an attempt to to change from RAID to AHCI, I was told to go to the CMD prompt and change the registry to Safe Mode: bcdedit /set {current} safeboot minimal

Then in the BIOS I made the change from RAID to AHCI.

When I exited the BIOS, Windows tried to do a repair and failed, no doubt because of the change from RAID to AHCI.

So I ended up re-installing from the hidden system file as delivered. That started a process which eventually tried booting into Windows. However, I got a message saying it could not complete the repair with Windows in Safe Mode. So I am locked out of Windows.

Crazy me - but that is the situation I am in.

The question: Is it possible to get to CMD prompt to enter: bcdedit /deletevalue {current} safeboot
without going through Windows, because I no longer have an operational Windows as the repair never completed?

I did have some sense to do a Macrium clone of the 512gb pci. So if I have to, I can go through that process.





Replies (8)

Thanks for your post.  My issue that brought me here was that I could not enable write caching in windows on my Aurora R10 HDD seagate 2TB spinning disk which was seen as a single raid drive by windows  The NVME C: drive was also using the windows raid drivers.  However, neither were running an actual raid configuration.  The NVME did have write caching enabled, but windows wouldn't let me adjust the spinning disk settings for the seagate 2TB drive.

After changing to AHCI, windows automatically set write caching enabled on the drive once it stopped using the raid driver.  The key thing I wanted to solve was slow disk access as I would only get about 80mb/s write speeds, which was simply horrible.  After changing the controller out of raid mode in the bios and having windows enable write caching, I now achieve the expected 200mb/s average.




@Mike2008C6  ha!  If you'd only said "C6", I might not have noticed the Corvette connection unless maybe I'd just been doing car stuff -- although even then it would have been a long shot.  But since 2008 was a C6 year, I figured that combination might not be a coincidence.

In terms of your question, if you intend to dual boot with Linux, Optane probably isn't the way you want to go.  When RAID is enabled, the Intel RST controller sits in front of all storage in the system, even if it's not running any RAID setups, which means that for the OS to access any storage, it needs to have the appropriate driver to talk to that RST controller.  To my knowledge Linux still has no Intel RST driver, so it won't work while the system is in RAID mode (unless you wanted to install Linux onto a USB hard drive or something).  I suppose in theory you could keep the Optane drive for your Windows setup if you were also willing to switch between RAID and AHCI modes every time you wanted to switch OSes, but I imagine that would get tiresome fast.  So I'd go with your plan of replacing it with a "conventional" SSD and running in AHCI mode.  You might even find that you can sell the Optane drive to finance a good chunk of the replacement.  Good luck!


jphughan: Not many pick up on the '2008C6' part of my name.
Love my C6 - it has been a really fun car to drive. Sleeping for the winter, but Spring is around the corner.....
I'm working on the restore of the system and will let you all know what happens. Thank goodness I had the sense to make a Macrium bootable USB and clone the PCI.
I have booted the Macrium USB and I am about to change the registry entry as per your suggestion. I'm not quite sure if that makes sense since Windows was in the process of rebuilding the system in AHCI mode but could not complete because of the Safe Mode flag. If I delete the flag, and change to RAID mode, and exit, Windows will probably continue that rebuild that it was doing while in AHCI mode. I'm not sure what will happen but I will let you know. I may just have to restrore the clone.
Now on another matter:
My plan is to end up with a dual boot ubuntu/windows laptop. I am actually an avid ubuntu user which I have on my Desktop. The laptop is for my wife and I am urging her to migrate from Windows to Ubuntu. So the fact that ubuntu won't work with RAID and the Dell requires Raid does not make me happy. I would have not bought the machine had I known that.
Can I install Ubuntu on a SATA SSD (to be installed shortly) and boot either from the Windows 10 PCI or the SATA SSD Ubuntu? Will Ubuntu boot at all when RAID is set, or is the RAID only impact the optane/pci?
If that doesn't work than I will have to chuck the optane/pci, stick in a 1tb Samsung in place, and change the RAID to AHCI.
This is a really great forum. Thanks for all your help. I will keep you posted.

@Saltgrass  doesn’t work if the OP is trying to use Optane. That requires RAID.

5 Rhenium

You should be able to boot to a recovery drive or the Win 10 install media and run the bcdedit command from the command prompt.

When you run the command, the {current} entry may not be accurate, it could be {default} instead.  Just running bcdedit should show the actual entry.

You have or have not returned the SATA controller options to their original settings?

XPS 9365, Inspiron 7567 Gaming, Inspiron 7779, XPS One 2720
System fully Win 11 compliant
7 Plutonium

@Mike2008C6  Didn’t mean to have a triple post here, but....2008C6. Corvette fan? I’m a performance driving instructor primarily at Circuit of the Americas. Started with a 2011 M3 (loved that high-revving V8), now running a 2016 Cayman GT4.

7 Plutonium

@Mike2008C6  in addition to the reply I just posted, I just reread your post and saw that you have an Optane setup.  In that case, you have to stick with RAID mode because Optane isn't just a single drive.  It's two separate storage devices (a small very fast cache and slower SSD storage) that just happen to be packaged together on the same physical circuit board.  That's why Optane storage specs always have two storage capacity figures -- and the only way those two storage devices can be treated as a single entity as intended is through the Intel Rapid Storage controller, which is only active in RAID mode.  That's why Windows didn't boot properly when you switched to AHCI despite your prep work.  So just leave it as RAID and install your second disk when you get it.  You'll still be able to use it separately.

7 Plutonium

RAID mode just means that the Intel Rapid Storage controller is active.  It doesn't automatically force you to use RAID even if you add a second disk, so you really don't need to be jumping through hoops to use AHCI just because you plan to install another disk.  As to why systems ship that way, it's mostly related to factory standardization and history.  When RAID mode is used, systems that DO have multiple disks installed CAN be configured in RAID, and Dell does sell some systems that can be configured with an actual RAID virtual disk set up from the factory.  RAID mode is also required to use things like Intel Optane and its predecessor Intel Smart Response, both of which involve using a fast SSD cache to accelerate a larger quantity of slower, cheaper storage in order to get SSD-like performance at a lower cost.  And RAID was also used to allow installing Windows 7 onto NVMe SSDs.  Windows 7 didn't have native NVMe support, but when RAID mode was active, that didn't matter because Windows 7 just saw a RAID controller (even if there was only a single disk behind it or multiple disks not in a RAID), and that controller abstracted the NVMe interface from the OS.  The only downsides to using RAID are that a) you can't run Linux, b) you can't use certain proprietary drivers and applications (like Samsung Magician if you install a retail Samsung SSD), and c) you may have to manually provide the Intel RST driver when performing a clean Windows install.  But Dell doesn't sell very many systems with Linux installed from the factory, they don't use retail Samsung SSDs, and incorporating one more driver into their factory builds is trivial.  So like I said, they just standardize on RAID for consistency.

But if you really want to switch, you should have been able to just open MSConfig while your Windows environment was working in RAID mode, choose to enable Safe Boot there, then restart your system, switch to AHCI, let Windows load once in Safe Boot and switch drivers around, then reboot again in normal mode.  If that didn't work for you, I'm not sure what happened.  If you try switching back to RAID, you might find that your Windows installation starts working despite the changes you made.  Otherwise if you made a Macrium Reflect image backup, just restore that and set your system back to RAID before booting.  As I said, having your system in RAID mode won't force you to actually set up a RAID virtual disk when you install a second drive.

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