two installs on one ssd

helpful55 · 21 Feb 2024

I have an ssd with a uefi os install. I would like to make another partition and do a separate install for a different pc (cloning it over) while leaving the original os in case of reverting back to that original pc. As I remember when you get the black screen allowing you to pick which os to start there may be no way to know which is which. I don’t want pc #2 starting os #1 and installing drivers/messing things up for #1. Can I modify which partition is active in disk manager so it always goes to the #2 install? Or if not how do I make sure I only get #2 os to start? I can make the partitions different sizes so I know for sure which is which when I am in disk manager. And remember I don’t think the select screen tells me which is which. Thanks for some help here.

SIW2 · 21 Feb 2024

Can I modify which partition is active in disk manager so it always goes to the #2 install?

On an mbr disk the boot critical files are inside a folder called Boot on the active partition. .
Bootmgr on the active partition consults the bcd store on the active partition.
If there more than one os entry in the bcd store, then bootmgr will show you a menu.
You can set the descriptions of the boot menu entries so you know which is which.
You can also set which is default and the time out.

For efi booting from a gpt disk:
the boot critical files are inside a folder called EFI on the esp partition. .
bootmgfw will consult the bcd store on the esp partition
If there is more than one os entry in the bcd store, then bootmgfw will show you a menu.
You can set the descriptions of the boot menu entries so you know which is which.
You can also set which is default and the time out.

helpful55 · 22 Feb 2024

Is this what I can use to do this?

Dual Boot - Change OS Name in Windows Boot Manager.

#1 pc is disassembled but I can easily set it back up temporarily to set the name for its W7 install. That way I know not to boot to that after I clone over #2 to a different partition which I will also rename after booting to it. I suppose this could also be done using the ssd connected to another pc as an external drive if I can select which drive I want to modify.

Volume Z · 22 Feb 2024

helpful55 said:

Can I modify which partition is active in disk manager so it always goes to the #2 install?

Yes you can. But the partition must be marked active before installation starts. A second boot manager for the second OS will be created on the active partition and the boot manager of OS 1 will be left alone until the "active" mark gets restored. No boot selection will show up.

helpful55 · 22 Feb 2024

Volume Z said:

Yes you can. But the partition must be marked active before installation starts. A second boot manager for the second OS will be created on the active partition and the boot manager of OS 1 will be left alone until the "active" mark gets restored. No boot selection will show up.

Would that work if I am just cloning over os #2? And if so what of that os do I clone over to the new partition? In disk manager it shows as having a 100mb efi system partition and the os primary partition. Do I need a new 100mb partition replicated also? I do kind of like the idea of having that #1 os as inactive unless I need it so it can't be messed up by mistake.

Volume Z · 23 Feb 2024

Nothing of what I wrote applies to a GPT style disk with an EFI System Partition. Active is an element of the MBR world. Even adding a second EFI System Partition will not prevent confusion as Windows Boot Manager will appear twice in UEFI.

You may just rename the boot entries in Windows Boot Manger so they can be distinguished. Or if deemed necessary, temporarily remove the respective unused entry.