Question Migrating windows install (partition/bootloader question)

Jan 16, 2011
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#1
So I recently upgraded some parts, including getting an NVMe SSD, which I'd like to make into my primary system drive.

Currently I'm dual-booting the old and the new windows, while in the process of transferring all settings, documents and data.

One thing I've noticed while playing around with the disks and partitions is that the old drive has the EFI system partition, which presumably holds the windows boot manager. (Is this correct?)

What's gonna happen when I finish the migration and format that drive (thus wiping out the EFI partition)?

Follow-up question:
The old install was having trouble booting when I switched the storage mode from AHCI to RAID. After messing around, and forming some hypotheses on how the windows boot process works, I was able to find a workaround. I do not exactly know how everything works, so I've been working on conjecture and extrapolation.
Conjecture: The EFI partition contains the windows bootloader which is like its own mini-OS with its own drivers and stuff.
My drive was failing to boot in RAID mode, because the bootloader was lacking raid drivers to access that drive and initiate the kernel from it.
So what I did was boot from a windows install USB, as if starting a new windows install, got to the part where it asks me to choose which drive to install the OS on - at that point you get a "Load driver" option. I loaded the drivers, then aborted the OS install process - lo and behold, my old install was now booting in RAID mode (presumably because I'd just installed the RAID drivers to the bootloader).
So the question is: Is there an easier way to install drivers on the bootloader?
 

RLGL

Golden Member
Jan 8, 2013
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#2
Bite the bullet and do a fresh install
 

deustroop

Golden Member
Dec 12, 2010
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#3
By dual booting, do you mean two installed drives each with Win 10 or two drives, one booting win 10 ( the old drive ) and the other one acting as storage ?

Deleting the EFI partition would have the effect of removing the booting capability of the drive for which it was installed, presumably the old drive. That is so obvious I suspect you mean something else. Of course if you installed windows on the new drive while the old one was also installed , that partition could operate the new installation instead or as well.

To have an automatic RAID mode setup from a windows 10 install, set SATA mode to RAID in bios prior to install.
 
Jan 16, 2011
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#4
By dual booting, do you mean two installed drives each with Win 10 or two drives, one booting win 10 ( the old drive ) and the other one acting as storage ?

Deleting the EFI partition would have the effect of removing the booting capability of the drive for which it was installed, presumably the old drive. That is so obvious I suspect you mean something else. Of course if you installed windows on the new drive while the old one was also installed , that partition could operate the new installation instead or as well.

To have an automatic RAID mode setup from a windows 10 install, set SATA mode to RAID in bios prior to install.
Got a new NVMe to boot from instead of old sata SSD. The situation should be pretty obvious here.

What does the EFI partition contain anyway? From what I've seen, you can't boot without it. Now between both drives - there's only one of those, on the old drive. I'm afraid if I destroy it, I won't be able to boot the new win install either.

As for my second question - well, the only thing I've been able to find is exactly what I already did: https://docs.microsoft.com/en-us/windows-hardware/drivers/install/installing-a-boot-start-driver

@RLGL, you're not helping.
 

ArisVer

Golden Member
Mar 6, 2011
1,201
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#5
I am not trying to be a pain in the butt, but I am confused. You assume that we know what your system is.

So far I can understand that you got a new NVMe SSD and that you have an old SATA SSD. And that you probably cloned your old ssd to your new ssd.

Please state.
Your disks, including brands if possible.
What Windows or other operating systems you have in each of your disks and what software you used to do any cloning (you actually said migrating).

As far as the partitions go, I wouldn't pay much attention to that, since the cloning software or the Windows installation will copy them or install them as they are needed.

And as RLGL said, a new installation is much better, especially with a new disk. But I can also understand why you might want to transfer your existing installation.
 
Aug 25, 2001
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#6
So what I did was boot from a windows install USB, as if starting a new windows install, got to the part where it asks me to choose which drive to install the OS on - at that point you get a "Load driver" option. I loaded the drivers, then aborted the OS install process - lo and behold, my old install was now booting in RAID mode (presumably because I'd just installed the RAID drivers to the bootloader).
Honestly, that's the first that I've heard, that it works that way. Generally, the "Load Drivers" option, loads from a USB stick or a DVD - into RAM, and then those same drivers are copied onto the target (installation) HDD/SSD for OS further (2nd-stage) installation.

I haven't ever heard that simply booting a USB stick with a Win10 install, and then choosing "load drivers", actually will write those drivers to the EFI or system boot partition, particularly of an installation not the target of the install (secondary drive).

To me, your explanation makes no sense, but I'm always ready to learn something new. Maybe something about this has changed, in Win10? Anyone know?
 
Jan 16, 2011
85
2
66
#7
I am not trying to be a pain in the butt, but I am confused. You assume that we know what your system is.

So far I can understand that you got a new NVMe SSD and that you have an old SATA SSD. And that you probably cloned your old ssd to your new ssd.

Please state.
Your disks, including brands if possible.
What Windows or other operating systems you have in each of your disks and what software you used to do any cloning (you actually said migrating).

As far as the partitions go, I wouldn't pay much attention to that, since the cloning software or the Windows installation will copy them or install them as they are needed.

And as RLGL said, a new installation is much better, especially with a new disk. But I can also understand why you might want to transfer your existing installation.
I see where the confusion is coming from.
I have an old sata SSD with an old windows install.
I got a new nvme ssd and put a new windows install on it.

Take a look at the image. My question is - what happens when I format Disk 0? (Bonus: How does the Windows boot process work anyway?)

Honestly, that's the first that I've heard, that it works that way. Generally, the "Load Drivers" option, loads from a USB stick or a DVD - into RAM, and then those same drivers are copied onto the target (installation) HDD/SSD for OS further (2nd-stage) installation.

I haven't ever heard that simply booting a USB stick with a Win10 install, and then choosing "load drivers", actually will write those drivers to the EFI or system boot partition, particularly of an installation not the target of the install (secondary drive).

To me, your explanation makes no sense, but I'm always ready to learn something new. Maybe something about this has changed, in Win10? Anyone know?
I've seen conflicting information myself. I did speculate on the underlying architecture, but the only thing I can claim for certain is the observations you quoted.
 

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