booting a system with 2 EFI partitions

Hi Guys,

I have a 2nd SSD that I want to add to an existing PC (UEFI). This SSD is a boot drive from another PC and has an EFI partition.
I only want to access data on this drive but I still want it to be bootable when it goes back in it's original system.

The bios is pointing to the original internal m.2 drive and this 2nd SSD is not in the boot list.

Is this okay without changing anything or would the existence of 2 efi partitions on the system cause a problem?

Also if the boot sequence is changed on the original system so that EFI partition is updated is there any chance that the 2nd SSD could also have it's EFI partition updated too? If so what would I need to do to prevent this?

Thanks

btw I do not want to mount this by usb after boot

tenjay said:

Hi Guys,

I have a 2nd SSD that I want to add to an existing PC (UEFI). This SSD is a boot drive from another PC and has an EFI partition.
I only want to access data on this drive but I still want it to be bootable when it goes back in it's original system.

The bios is pointing to the original internal m.2 drive and this 2nd SSD is not in the boot list.

Is this okay without changing anything or would the existence of 2 efi partitions on the system cause a problem?

Also if the boot sequence is changed on the original system so that EFI partition is updated is there any chance that the 2nd SSD could also have it's EFI partition updated too? If so what would I need to do to prevent this?

Thanks

btw I do not want to mount this by usb after boot

Hi there

@tenjay

what I would do in this situation is to run both these systems as VHDX (Virtual hard drives) -- not Virtual machines - and then when you boot you will get a choice of which system to boot. You probably could manage with editing the boot menu but using Virtual hard disk drives IMO is the best way of keeping the two systems totally isolated from each other.

Needs a bit of work first but it's a great way of also having several Windows systems which you can test using "Real hardware.

Essentially clone both systems to VHDX files, clear the primary boot disk , create a winpe bootable usb device, copy the VHDX files to the relevant disks, attach to the winpe system and then create the boot entries. Then shutdown, remove the winpe device and re-boot. You'll now see a boot menu with your 2 systems. Just boot whichever one and all done !!!. You can also have several VHDX systems per disk -- all you need is that the VHDX files are big enough for your Windows install. Then they behave just like normal Windows systems. Advantage also is no overhead of any "HOST OS" either. Note these are NOT VM's but physical installations.

Good thing also about this is you do not need to enter BIOS to choose Boot disk !!!.

Example here -- I have an 80GB W11 system on a VHDX (I'm using it now) - and an internal 256GB SSD . As I only have 1 SSD on this laptop I have the 80GB VHDX file defined on it. I'm in the process of creating another 80GB VHDX to install the Windows 11 DEV system.

To create the VHDX files do it from Disk management (right mouse click on the W11 / W10 menu icon depending on the OS you are running. Choose VHDX rather than VHD at creation and choose allocate completely as a single file. You don't need HYPER-V or any VM software for this.

The Main Disk D is not used by the VHDX's in running the systems but the unallocated parts can be accessed via file explorer as normal - no mount needed.



Cheers
jimbo

jimbo45 said:

Hi there

@tenjay

what I would do in this situation is to run both these systems as VHDX (Virtual hard drives) -- not Virtual machines - and then when you boot you will get a choice of which system to boot. You probably could manage with editing the boot menu but using Virtual hard disk drives IMO is the best way of keeping the two systems totally isolated from each other.

Needs a bit of work first but it's a great way of also having several Windows systems which you can test using "Real hardware.

Essentially clone both systems to VHDX files, clear the primary boot disk , create a winpe bootable usb device, copy the VHDX files to the relevant disks, attach to the winpe system and then create the boot entries. Then shutdown, remove the winpe device and re-boot. You'll now see a boot menu with your 2 systems. Just boot whichever one and all done !!!. You can also have several VHDX systems per disk -- all you need is that the VHDX files are big enough for your Windows install. Then they behave just like normal Windows systems. Advantage also is no overhead of any "HOST OS" either. Note these are NOT VM's but physical installations.

Good thing also about this is you do not need to enter BIOS to choose Boot disk !!!.

Example here -- I have an 80GB W11 system on a VHDX (I'm using it now) - and an internal 256GB SSD . As I only have 1 SSD on this laptop I have the 80GB VHDX file defined on it. I'm in the process of creating another 80GB VHDX to install the Windows 11 DEV system.

To create the VHDX files do it from Disk management (right mouse click on the W11 / W10 menu icon depending on the OS you are running. Choose VHDX rather than VHD at creation and choose allocate completely as a single file. You don't need HYPER-V or any VM software for this.

The Main Disk D is not used by the VHDX's in running the systems but the unallocated parts can be accessed via file explorer as normal - no mount needed.



Cheers
jimbo

Okaaay? I've not heard of this and never bothered with VMs although you say this is not a VM. So I will look into this. just at the moment though I think it will be a bit complicated for my immediate needs.

But some question please that could help me decide if I should look at this. - thnx
Is each VHDX file acting as a separate OS then?
Can all machines work with VHDX files? I still need my 2nd SSD to work with my laptop which is quite old (i7 gen3)
What about backing up these partitions? They are 800GB but the data is only 200GB currently. When I backup with macrium I get smallish files. If I used VHDX would I have to backup the whole 800GB files?

cheers

edit...... did you update your post? I did not see the screen shots. maybe what I asked above could be redundant. I'll take a look now though thnx

edit 2...... My head hurts a bit lol. I just checked my laptop and yes it does have VHD so that's good. This sounds very interesting but I'll have to do some googling - I've only just got my head round dual booting from UEFI rather than MBR.
Thanks for pointing this method out. I may work for me longer term.

tenjay said:

Okaaay? I've not heard of this and never bothered with VMs although you say this is not a VM. So I will look into this. just at the moment though I think it will be a bit complicated for my immediate needs.

But some question please that could help me decide if I should look at this. - thnx
Is each VHDX file acting as a separate OS then?
Can all machines work with VHDX files? I still need my 2nd SSD to work with my laptop which is quite old (i7 gen3)
What about backing up these partitions? They are 800GB but the data is only 200GB currently. When I backup with macrium I get smallish files. If I used VHDX would I have to backup the whole 800GB files?

cheers

Hi there
@tenjay

Each VDHX is a totally separate OS

Screenshots should be on the post

No problem with older machines using this -- I'm on a laptop with an old i5 processor.

The VHDX files only need to be the size you need for your windows OS'es. I'd just keep the OS files small and discrete and keep the rest of the HDD 's for data.

For backup -- you don't even need to backup the actual OS's because if you backup the disks with the vhdx files on them that's sufficient. If you hose up an OS just restore the relevant VHDX file .

While you could use the whole HDD for the VHDX file --there's no point -- It's always better to keep OS and data separate anyway -- and remember also the unused parts of each disk can be accessed by both OS'es.

This stuff takes a while to get used to but it IMO is infinitely better than the "Classical dual boot" scenario and a lot more flexible.

Here's a bit of documentation -- forget the SYSPREP bit -- I'd just create Windows on a device "Normally" then with Macrium Clone it to a VHDX , and then follow the instructions using the bootable winpe - download in the link. Choose the W11 version even if only installing W10 .

https://docs.microsoft.com/en-us/win...-the-boot-menu

Cheers
jimbo

jimbo45 said:

Hi there
@tenjay

Each VDHX is a totally separate OS

Screenshots should be on the post

No problem with older machines using this -- I'm on a laptop with an old i5 processor.

The VHDX files only need to be the size you need for your windows OS'es. I'd just keep the OS files small and discrete and keep the rest of the HDD 's for data.

For backup -- you don't even need to backup the actual OS's because if you backup the disks with the vhdx files on them that's sufficient. If you hose up an OS just restore the relevant VHDX file .

While you could use the whole HDD for the VHDX file --there's no point -- It's always better to keep OS and data separate anyway -- and remember also the unused parts of each disk can be accessed by both OS'es.

This stuff takes a while to get used to but it IMO is infinitely better than the "Classical dual boot" scenario and a lot more flexible.

https://docs.microsoft.com/en-us/win...-the-boot-menu

Cheers
jimbo

Thanks jimbo. Our posts crossed as I edited the last one. Yes this certainly looks interesting. I will have to cope with big files though I think because It is a music setup and there are big sample libraries and resource files that need to stay with the applications. Even if I were to split them off I would still need to back them up. But yes this is definitely worth a look - thank you!

Or you can just attach the second SSD to the computer and access the data on it. The second EFI partition will not cause any problems.

NavyLCDR said:

Or you can just attach the second SSD to the computer and access the data on it. The second EFI partition will not cause any problems.

Thanks Navy. It's all part of trying to make this DELL work. Because the issue got worse (even longer boot time) I wondered if 2 EFIs was causing a further problem. From what you say that is unlikely then.

Working on it with easybcd I am seeing that most changes to one OS boot instructions are reflected across the disks and seen when booting into another OS. so do I have this right??......... does a change via the os get passed to the EFI partition and then onto the firmware (bios?) which then gets replicated across all EFI partitions it sees? That is the only way I can see each OS getting the changes. ....but then I don't know enough about it to understand another way.
cheers

I have a 2nd SSD that I want to add to an existing PC (UEFI). This SSD is a boot drive from another PC and has an EFI partition.
I only want to access data on this drive but I still want it to be bootable when it goes back in it's original system.

The bios is pointing to the original internal m.2 drive and this 2nd SSD is not in the boot list.

Is this okay without changing anything

Yes it is fine to use it for accessing data.

would the existence of 2 efi partitions on the system cause a problem?

No. I have several on this machine. To avoid booting into it the second disk by accident, check your bios/efi firmare is set to boot from the original disk

The bios is pointing to the original internal m.2 drive and this 2nd SSD is not in the boot list

- from your post you seem to have checked that.

Also if the boot sequence is changed on the original system so that EFI partition is updated is there any chance that the 2nd SSD could also have it's EFI partition updated too?

No. The esp partition on the second disk will not change by itself. You would have to do it deliberately

spunk said:

As stated, attach the secondary drive and then boot into Setup (Bios) make sure the Secondary HDD is lower in the Boot Order options and not the first Boot device. Save and Exit. The computer will boot from the original SSD and have nothing to do with the secondary SSD it will come up as a secondary drive. Copy the files off of it and then return the secondary drive to it's original computer.
BTW, if all you want to do is to copy data off of this drive, and it boots fine in the computer it came from, then just copy the data you want in that computer and save it to a USB Flash drive, then transfer it over to the other computer.
Or if both computers are viewable on your Routers Network, Share files on each computer drag and drop the files from one computer to other across your network.

cheers

- - - Updated - - -

SIW2 said:

Yes it is fine to use it for accessing data.





No. I have several on this machine. To avoid booting into it the second disk by accident, check your bios/efi firmare is set to boot from the original disk - from your post you seem to have checked that.






No. The esp partition on the second disk will not change by itself. You would have to do it deliberately

Thanks