This is a thing I have to do from time to time, and up to now I’ve been depending on two different sets of instructions (because one was not correct for Windows 10, and the other isn’t complete). So I’ve finally written my own instructions, and here they are.

Disclaimer

This is a somewhat advanced procedure.  Try it at your own risk.  I will not be responsible if this kills your computer, eats your family pictures for seven generations, or causes the heat death of the universe… or any other bad thing, big or small.  This is the procedure I used yesterday, and as far as I know it’s good, but follow it at your own risk.

Introduction

First, it’s important that the partition structure of the boot drive be “normal,” that is, the way Windows 10 would create it. The instructions below won’t work right if the partitions are in a different order. Unfortunately, many system builders (including my distributor) use a non-standard partition layout.

So for me, at least, the first thing to do is to erase the hard drives with zeros (I use a Linux boot flash drive for this) and then reinstall Windows 10 on the primary drive. This task will not be described here, as it’s a very basic procedure.

Assuming we are starting with the first hard drive having a more or less default Windows installation (on a GUID formatted drive), and the second being entirely blank, here’s how we do it:

Duplicate the Recovery Partition:

Open an administrative command prompt window, then run the diskpart command. We need the information about the Recovery Partition, so execute these commands:

You should get something like this:

Volume ### Ltr Label Fs Type Size Status Info
———- — ———– —– ———- ——- ——— ——–
* Volume 4 Recovery NTFS Partition 529 MB Healthy Hidden

Take careful note of the Type ID (i.e. Type, above) as well as its size.

Now make sure the second drive is GPT and completely empty, then create a new Recovery Partition there:

We’ll need drive letters assigned to both the original and the duplicate recovery partitions:

That last command will take you out of diskpart. Now we need to use robocopy to make a duplicate of the original recovery partition:

Duplicate the EFI System Partition:

Next, we need to duplicate the EFI System Partition. Back into diskpart:

You’ll get something like this:

Note the sizes of the System and Reserved partitions, and recreate them on the second drive:

We need the primary disk System partition to have a drive letter:

Now we’re out of diskpart again, off to robocopy:

Mirror the Operating System Partition:

Most instructions say to close the Admin CMD window at this point, but you can honestly just ignore it; you’ll need it again later, so close it or leave it
open, does not matter.

You need to launch diskmgmt.msc now, or just go to Computer Management and select the Disk Manager section. Right-click on the primary disk and choose Convert to Dynamic Disk, then do the same for the secondary disk. Finally, right-click on the C: volume and choose Add Mirror to choose a drive for the mirror. Select Disk 1 and click the Add Mirror button.

This is the boring part. You need to wait for the mirroring to complete before moving on to duplicating the BCD boot instructions (in the next part, below).

Prepare the BCD Boot Entries

The procedures done so far have created a proper mirror of the boot drive, and a boot menu item has been added to allow you to boot from the secondary plex (drive). However, if the primary drive fails, booting from the secondary drive may fail as well. It is possible to use a boot CD and repair the boot on the secondary drive, and this is always an option, but duplicating the BCD boot information on the secondary drive should remove any need for this.

If the Admin command prompt has been closed, you’ll need to reopen it; if the system has booted, you’ll need to reassign the drive letters for the EFI partitions. To do this, run diskpart and enter the following commands:

Now you’re back at the command prompt. Type the following commands:

That last command should give you something like this (warning, long):

Windows Boot Loader
——————-
identifier {current}
device partition=C:
path \Windows\system32\winload.efi
description Windows 10
locale en-US
inherit {bootloadersettings}
recoverysequence {6fb37503-3d6b-11ea-914e-85f8d8cf8c72}
displaymessageoverride Recovery
recoveryenabled Yes
isolatedcontext Yes
allowedinmemorysettings 0x15000075
osdevice partition=C:
systemroot \Windows
resumeobject {6fb37501-3d6b-11ea-914e-85f8d8cf8c72}
nx OptIn
bootmenupolicy Standard

Windows Boot Loader
——————-
identifier {6fb37506-3d6b-11ea-914e-85f8d8cf8c72}
device partition=C:
path \Windows\system32\winload.efi
description Windows 10 – secondary plex
locale en-US
inherit {bootloadersettings}
recoverysequence {6fb37503-3d6b-11ea-914e-85f8d8cf8c72}
displaymessageoverride Recovery
recoveryenabled Yes
isolatedcontext Yes
allowedinmemorysettings 0x15000075
osdevice partition=C:
systemroot \Windows
resumeobject {6fb37501-3d6b-11ea-914e-85f8d8cf8c72}
nx OptIn
bootmenupolicy Standard

The boot loader entry entitled “Windows 10 – secondary plex” was added when the C: drive was mirrored. Now we clone the working Windows Boot Manager:

You’ll get a reply like this:

The GUID at the end will vary, of course. Use it in the following command:

Now we need to export the BCD store to copy it to the T: drive:

This should complete the operation. Rebooting the system to remove any excess drive letter assignments is recommended.

So say you have a Windows Update that isn’t finishing.  In the Windows Update Settings screen, beneath the update it says “Status: Awaiting Restart,” but you restart, and when you look it still says that.  Here’s the fix, collected from several different answers I found online:

First, you need an elevated command prompt.  Click start and type CMD in the search, but don’t press Enter; instead, right-click on the Command Prompt item that search should have found and choose Run as Administrator.  Say Yes to the prompt about making changes to your system… that’s exactly what we’re doing here.

Now you have a command window.  Enter the following commands one after another:

SC config wuauserv start= auto
SC config bits start= auto
SC config cryptsvc start= auto
SC config trustedinstaller start= auto

Now, restart your computer.  During the restart you should see the update actually running.