keeping dual boot drives independently bootable

[Muffin Top]

I found a dual-booting recommendation in Microsoft community, below, for keeping the two drives independently bootable. He doesn't say why he personally recommends this, but it's in alignment with my objective of dual-booting via BIOS.


He says to install each operating system with the other disk unplugged, to avoid having the EFI system partition on the first disk from controlling both disks. He says to set your preferred operating system to start automatically, and use the one-time BIOS menu to start the other.


I know some will view this as a hassle, but it's in alignment with my objective for dual-booting via BIOS.


Anyone see any pitfalls with his recommendation (other than having to go into BIOS to start the disfavored system) ?


Has he inadvertently omitted any important steps or considerations ?


Redirecting

 

[SIW2]

Should be fine.

You can use the one time boot menu for convenience

some f key to tap as post finishes . Maybe f12 depends on the machine

List of PC brands with their corresponding hot-keys

 

[Muffin Top]

Thanks, F12 on mine.

I appreciate the guidance. I accidentally installed 7 in MBR while my 10 GPT NVMe was plugged in, so it seems that I've fouled the boot manager, making 10 partially inaccessible. It will be interesting to see if I can fix it with system restore or reset. If not, I didn't have any data on the 10 system, so it's no loss if I have to re-install.

I had forgotten about the link's guidance to install each system with the other drive unplugged.

I think that link's recommendation is in alignment with my objective of dual-booting via BIOS instead of relying on the windows' dual-boot manager.

 

[SIW2]

It will be interesting to see if I can fix it with system restore or reset.

probably dont need to do all that. bcdboot command from installation media will probably do it.

 

[Muffin Top]

Thanks, it's been a learning experience. How would that work ?

Do I begin with bootcfg query to learn how I corrupted the bcd ?

Or do I just launch straight into :
(1) bootrec /rebuildbcd
(2) bootrec /fixmbr
(3) bootrec /fixboot

It sounds like I'll want to unplug my Win 7 disk before I run the commands above, to accomplish my objective of keeping the 7 & 10 disks independently bootable.

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I don't just type bcdboot d:\windows ?

I would at least need to unplug the Win 7 disk (disk C. Then run diskpart again to see if the Win 10 disk is still D: .

Do I also need the three bootrec commands above ?

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What does it mean if bootcfg /query cannot open boot.ini file ?

 

[SIW2]

win10/11 Bcdboot - Bcd boot file creation and repair tool.

The bcdboot.exe command-line tool is used to copy critical boot files to the
system partition and to create a new system BCD store.

bcdboot <source> [/l <locale>] [/s <volume-letter> [/f <firmware>]] [/v]
[/vbcd] [/m [{OS Loader ID}]] [/addlast] [/p] [/c]

source Specifies the location of the windows system root.

/l Specifies an optional locale parameter to use when
initializing the BCD store. The default is US English.

/s Specifies an optional volume letter parameter to designate
the target system partition where boot environment files are
copied. The default is the system partition identified by
the firmware.

/v Enables verbose mode.

/vbcd Enables BCD logging.

/m If an OS loader GUID is provided, this option merges the
given loader object with the system template to produce a
bootable entry. Otherwise, only global objects are merged.

/d Specifies that the existing default windows boot entry
should be preserved.

/f Used with the /s command, specifies the firmware type of the
target system partition. Options for <firmware> are 'UEFI',
'BIOS', or 'ALL'.

/addlast Specifies that the windows boot manager firmware entry
should be added last. The default behavior is to add it
first.

/bcdclean Clean the BCD Store. By default, simply removes any duplicate
entries in the BCD. Can be followed by 'full'. In this case,
each entry is scanned. If the corresponding device for that entry
does not exist, the entry is deleted.

/p Specifies that the windows boot manager firmware entry
position should be preserved. If entry does not exist,
new entry will be added in the first position.

/c Specifies that any existing objects described by the template
should not be migrated.

Examples:

bcdboot c:\windows /l en-us
bcdboot c:\windows /s h:
bcdboot c:\windows /s h: /f UEFI
bcdboot c:\windows /m {d58d10c6-df53-11dc-878f-00064f4f4e08}
bcdboot c:\windows /d /addlast
bcdboot c:\windows /p

 

[Muffin Top]

I'm nervous about bcdboot because it seems to be spec'd for 7 & 8.

Not sure if it works for 10 & 11 when a lot of other sources have moved onto bootrec.

Well I tried bootrec and it could only see my Win 7 set-up. It can not see my Win 10 set-up, so I guess I need to run the second and third commands of /fixmbr and /fixboot.

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And no boot.ini file on the Win 10 disk

Only a bootmgfw.efi

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Ok, I'll give it a try. I'd better unplug my Win 7 disk first, before I mess it up!

 

[Volume Z]

Sorry you just don't know what you are doing and we don't know either. You are not providing an image of disk management. Bootcfg and boot.ini have been obsolete since Windows Vista. Bootrec does not apply to the GPT partition style. Bcdboot is not specific to Windows 7 and 8. Sources haven't moved to bootrec; they have moved away from it. And so on and so forth.

 

[Muffin Top]

There are a lot of youtube vids depicting the bootrec command. And SIW provided something about Win 10/11.


Windows 10's diskpart shows my Win 10 disk still has its EFI partition.


However, Windows 7's diskpart and diskmgmt are not able to see my Win 10 disk.

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My Win 7 system doesn't have a NVMe driver. I think that's why it can't see the Win 10 NVMe drive.


In Win 10's diskpart, it still appears to be unchanged. I've got some minor boot problem caused by installing Win 7.

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I guess I could just use system restore or reset. If bcdboot or bootrec doesn't work.


I gotta remember to keep one disk disconnected when I work on the other, until I've learned how to dual boot via BIOS without messing up my other disk.

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I was trying to follow the advice in the link, about keeping the two systems independently bootable.


Redirecting


I goofed by forgetting to disconnect my Win 10 disk when I installed Win 7. So my Win 10 system is still there, but I need to repair the boot.

 

[Muffin Top]

I think I figured out why the bcd fixes aren't working for me. I installed Win 7 on HDD named C: even though my Win 10 system was on NVMe named C:.

So my Win 7 system renamed the Win 10 NVMe drive as D:, so that's why it won't boot, and the traditional bcd boot repairs are irrelevant.

So my question, if anyone knows, if keeping both versions of Windows independently bootable, can I let them both be named C: ?

If not, I think I want Win 7 to be named C:, so I think that means I'll have to re-install Win 10 on D: ?

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I guess if I'm going to apply the strategery of setting up these independently bootable systems, then I'll need to have a spare dummy SSD inserted:

Step 1: Install Win 7 as C:
Step 2: Unplug Win 7 SSD, insert Win 10 NVMe and dummy SSD
Step 3: At Win 10 installation environment, assign dummy SSD = C:, so that Win 10 installer will allow me to assign a different drive letter to the Win 10 NVMe

 

[Bree]

I think I figured out why the bcd fixes aren't working for me. I installed Win 7 on HDD named C: even though my Win 10 system was on NVMe named C:.

So my Win 7 system renamed the Win 10 NVMe drive as D:, so that's why it won't boot, and the traditional bcd boot repairs are irrelevant.

So my question, if anyone knows, if keeping both versions of Windows independently bootable, can I let them both be named C: ?

If not, I think I want Win 7 to be named C:, so I think that means I'll have to re-install Win 10 on D: ?

You don't need to do anything. The drive letters will change depending on which OS you boot to. Whichever one you have booted to will see the partition it is running from as the C: drive. It will see the other OS's partition as the D: drive.

 

[Muffin Top]

Maybe the simplified version of step 3 is assign NVMe = D: ?

Then maybe I don't need a dummy SSD to install Win 10 on the NVMe named D: ?

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You don't need to do anything. The drive letters will change depending on which OS you boot to. Whichever one you have booted to will see the partition it is running from as the C: drive. It will see the other OS's partition as the D: drive.

Thanks, I wasn't sure if I could do that without messing up the boot?

My situation is that installing Win 7 messed up my Win 10 boot. I think that happened because I don't have an NVMe driver in my Win 7 system, and it can't see my Win 10 disk.

Maybe I don't need to worry about the reverse? The Win 10 system can see the Win 7 system, so I won't mess up 7's boot?

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I guess I just needed to remove the Win 10 NVMe for Win 7 installation. After 7 installation, I could have both plugged in, dual-booting via BIOS, without either one messing up the other's boot ?

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You don't need to do anything. The drive letters will change depending on which OS you boot to. Whichever one you have booted to will see the partition it is running from as the C: drive. It will see the other OS's partition as the D: drive.

Thanks again, it seems to be working! Although I've encountered an unnerving paradox.

I unplugged my Win 7 disk, and repaired my Win 10 NVMe via a reset of windows. It would not let me repair via system restore, presumably because of the drive letter confusion that was caused when I accidentally installed Win 7 with the Win 10 drive plugged in.

After repairing my Win 10 NVMe, I verified sustainability of the two systems being independently bootable via BIOS. I went through several rounds of alternating boots of the two systems with both drives plugged in.

To review, my Win 7 system is MBR/legacy, and my Win 10 system is GPT/UEFI.

Beginning with the second (and all subsequent) boots of my 7 system, it noted the filesystem inconsistency, and wanted to do some checking. I cancelled these checks, and the warning does not seem to result in the two systems no longer being independently bootable.

So I now have most of my objectives. I'll be web browsing in my 7 system, and it can't see my 10 system, because my 7 system does not have the NVMe driver activated in device manager. My 10 system can see my 7 system, but that's ok because I won't be web browsing in my 10 system.

My preference for browsing in 7 is attributable to 7's version of system restore being the only one that's reliable. MicroSoft decided to de-prioritize the consumer segment, so the 10 & 11 system restore is not reliable.

I run system restore after every browsing session, and I'm pretty sure this op sec protocol works. Today, I downloaded Malwarebytes to the trusty Win 7 laptop I've been using for the past 16 years. Malwarebytes did not detect BIOS bugs or any other threats, even though I've encountered my share of malicious websites over the years. Running system restore after every session worked !

Now my next check is to see if I can install Win 7 in GPT/UEFI, because I'd like to run Win 7 using secure boot, if that's not too difficult to manage.

 

[SIW2]

presumably because of the drive letter confusion

No.

 

[MisterEd]

I don't know exactly how your computer is configured but is there room for a removable caddy? You can have multiple caddies with a different version of Windows on each one. Which one you boot depends upon which caddy you have plugged in.

BTW, I used to work in a secure environment where each project was on a separate caddy drive. To work on your project you plugged your drive.

Note since there is only one drive plugged in at a time then there is no confusion on which drive to boot from.

 

[Muffin Top]

Thanks so much, but it looks like I only need to make a one-time physical change. Install Win 7 with the Win 10 drive unplugged. After Win 7 is installed, then I can re-insert the Win 10 drive without having one of them mess up the other's boot.

I'm fine with dual-booting via BIOS, that was actually my objective.