Creating a dual boot system from 2 existing working installations

NavyLCDR said:

Whichever OS you are booted into gets the C: drive letter. If you boot into Windows 10, it will be C: drive and Windows 11 will be something else like E:. When you boot into Windows 11, it will get C: drive and Windows 10 will get something else.

Then I gather I can keep hibernation option as it may still be 2 files on 2 separate drives so may never collide like thought of initially .

nIGHTmAYOR said:

Then I gather I can keep hibernation option as it may still be 2 files on 2 separate drives so may never collide like thought of initially .

No. You boot into Windows 10. It has Windows fast startup enabled. When you shutdown the computer certain information regarding the state of the computer is captured in the hiberfil.sys file on the Windows 10 partition. That includes the states of the file systems and some files on all of the drives on the computer. Now you boot into Windows 11. Just by normal operations of the OS, the state of the computer and filesystems on different drives will change from when everything was saved in the Windows 10 hiberfil.sys file. Once you are done in Windows 11, it now saves the state of various system components in its own hiberfil.sys file on its own partition.

Now you go back to booting Windows 10. It reads the information stored in its own hiberfil.sys that was saved back when Windows 10 was shutdown. There will be things that have changed on the computer system since Windows 10 was last shutdown because you have since run Windows 11. The difference in the current system state (which is now a result of the last shutdown of Windows 11), and the state the system was in when you last shutdown Windows 10 can cause problems - one of which is that chkdsk can be triggered and you may have to wait for that to complete.

If you only had one OS on the computer, the state of the computer saved to hiberfil.sys when Windows shutdown would be the same as when you restart the computer, because there would be nothing to change the system between shutting down Windows 10 and starting Windows 10 again. But when you have 2 or more OSs on the system, there can be something that acts to change the state of the computer between shutting down Windows 10 and restarting Windows 10 - that would be the changes made by you running Windows 11 after Windows 10.

If the two Windows OSs could hare the same hiberfil.sys file it wouldn't be a problem. But since each OS has its own hiberfil.sys, it becomes a problem.

NavyLCDR said:

No. You boot into Windows 10. It has Windows fast startup enabled. When you shutdown the computer certain information regarding the state of the computer is captured in the hiberfil.sys file on the Windows 10 partition. That includes the states of the file systems and some files on all of the drives on the computer. Now you boot into Windows 11. Just by normal operations of the OS, the state of the computer and filesystems on different drives will change from when everything was saved in the Windows 10 hiberfil.sys file. Once you are done in Windows 11, it now saves the state of various system components in its own hiberfil.sys file on its own partition.

Now you go back to booting Windows 10. It reads the information stored in its own hiberfil.sys that was saved back when Windows 10 was shutdown. There will be things that have changed on the computer system since Windows 10 was last shutdown because you have since run Windows 11. The difference in the current system state (which is now a result of the last shutdown of Windows 11), and the state the system was in when you last shutdown Windows 10 can cause problems - one of which is that chkdsk can be triggered and you may have to wait for that to complete.

If you only had one OS on the computer, the state of the computer saved to hiberfil.sys when Windows shutdown would be the same as when you restart the computer, because there would be nothing to change the system between shutting down Windows 10 and starting Windows 10 again. But when you have 2 or more OSs on the system, there can be something that acts to change the state of the computer between shutting down Windows 10 and restarting Windows 10 - that would be the changes made by you running Windows 11 after Windows 10.

If the two Windows OSs could hare the same hiberfil.sys file it wouldn't be a problem. But since each OS has its own hiberfil.sys, it becomes a problem.

Sir this here dazzles me because of the following , I have been using hibernation with the 2 drives setup and it is flowless , apparently when one of my installed OSes hibernate it manages to communicate with bios and set which drive did hibernate and on next startup that drive boots by default without me even being able to change that from bios . So why is it an issue with a 1 drive setup ? couldn't I at least keep that feature on one of the OSes at least ?

nIGHTmAYOR said:

Sir this here dazzles me because of the following , I have been using hibernation with the 2 drives setup and it is flowless , apparently when one of my installed OSes hibernate it manages to communicate with bios and set which drive did hibernate and on next startup that drive boots by default without me even being able to change that from bios . So why is it an issue with a 1 drive setup ? couldn't I at least keep that feature on one of the OSes at least ?

You can feel free to keep the features on. It's just a recommendation. However, if you start to notice problems like I described, you know 1 troubleshooting step you can take.

NavyLCDR said:

When you shutdown Windows 10/11 with fast startup enabled, it writes system information to hiberfil.sys. When you log into the other OS, some of the information contained in the hiberfil.sys information written in the first OS becomes invalid. Then when you boot back into the first OS, it detects there have changes that have been made on the system and it may trigger chkdsk actions to occur. If you have SSDs, it's just best to disable hibernation and fast startup with the command provided because you really don't need fast startup with an SSD anyway, and it is especially beneficial on dual boot systems.

All of the extra partitions you are seeing are recovery partitions created by various upgrades to the OS. Running reagentc /disable takes the WindowsRE (recovery environment) out of the active recovery partition and puts it in C:\Windows\Recovery. Feel free to copy all those recovery partitions to the new SSD if you want to. All they will do is take up space that won't be used for anything.

Subsequently, after you move the OS partition to the new SSD, then you run reagentc /enable. This will re-enable the Windows Recovery Environment, but it will be located in C:\Recovery. You can verify this by running reagentc /info.

https://support.microsoft.com/en-us/...7-3cccfff54777

Microsoft claim they should be left untouched however

nIGHTmAYOR said:

https://support.microsoft.com/en-us/...7-3cccfff54777

Microsoft claim they should be left untouched however

Of course they do. So copy over all the extra partitions too then if you want to. They are doing nothing but occupying space on your drive so they won't hurt anything. They will have no useful purpose either but won't hurt anything. At least now with Microsoft upgrading Windows 10 only annually, you will only get a new one once per year.

If you leave recovery environment enabled and copy over all of the partitions as is, you're like to just break the recovery environment completely. I'm just suggesting ways to avoid potential problems after having set up hundreds of dual boot systems going back to beta testing Windows 95.

@NavyLCDR
I need to just understand this better regardless of dual boot , in this example partition 5 & 6 & in another drive 7 are nothing but older recovery environment , however each time I check partitions whenever I aim to clone or backup windows installation its always that the recovery and fat partition are 300 and 100 MBs respectively , so why would the extra partitions be bigger and more filled if they are just older versions of recovery ?
Attachment 351328

Because some of them contain contain specific system files applicable to the original factory software that was installed on the computer - referred to as bloatware by most people. "Oh....so I might need those files later!" Then ask yourself, "Hmmm......but how would I restore them?" Most older recovery partitions get broken when a full Windows 10 upgrade is completed. You can check which recovery partition Windows 10 is currently using with:
reagentc /info

You can keep all the partitions you want to keep. Most of the recovery partitions will be good for nothing more that taking up drive space. And if you don't disable recovery environment with "reagentc /disable" before you copy/clone your existing Windows partition to the new drive, you are increasing your chances of breaking the recovery environment which is not fun to repair.