Prior to MSFS install I made a habit of using Macrium Reflect to periodically clone the my primary boot drive on which I have the uber-laborious-to-set-up P3D installed on, to an identical sister NVme M.2 drive on the motherboard.  Never had a problem booting to either drive after cloning.  Since installing MSFS on the primary drive I have not done the clone operation as someone early on said they could not boot their MSFS-containing primary drive after doing a cloning operation with it.  I don't recall what software they used.  So I'm asking here if you could boot to both drives after cloning AND be able to run MSFS from both drives, these are the questions.   Anyway, I'd really like to do this but am a little paranoid after reading that comment.  It's very possible the chap did not correct reconfigure boot options after the cloning operation, but if you've had success or failure in this regard please respond.  Thanks

Edited November 11, 20205 yr by Noel

Hello,

Each partition is identified by an unique uuid.
Cloning a partition will normaly clone this uuid.

If your partition contains your Os (Windows, Linux, etc ...),
and if you do not remove the source drive, after cloning,
then your uefi bios does not know what partition it will use. It might use one or another one. Dangerous configuration !

You cannot boot both drives in this case !

So, if you want to keep both disks, you have to change all uuids on your destination drive that was cloned (several partitions needed for an os - several changes to perform)
And you have to add an entry in your ueefi bios, using a dedicated software such as efibootmgr under linux ... to be able to boot on that new drive.

If you want to remove your source disk, nothing else to do as both your uefi bios entries and uefi partitions on your disk are matched (remember, uuids were also cloned !)

Edit : some cloning software allow not to copy the partition uuid. Use this option if you know what you are doing, because if you remove your source drive, you will not be able to boot your clone disk (os) unless you modify all uefi bios entries to new uuids !
Do not play with bios entries and uuids unless you are familiar with the boot process, easybcd or efibootmgr, bios options !

Edited November 11, 20205 yr by ctdlg

2 hours ago, ctdlg said:

Hello,

Each partition is identified by an unique uuid.
Cloning a partition will normaly clone this uuid.

If your partition contains your Os (Windows, Linux, etc ...),
and if you do not remove the source drive, after cloning,
then your uefi bios does not know what partition it will use. It might use one or another one. Dangerous configuration !

You cannot boot both drives in this case !

So, if you want to keep both disks, you have to change all uuids on your destination drive that was cloned (several partitions needed for an os - several changes to perform)
And you have to add an entry in your ueefi bios, using a dedicated software such as efibootmgr under linux ... to be able to boot on that new drive.

If you want to remove your source disk, nothing else to do as both your uefi bios entries and uefi partitions on your disk are matched (remember, uuids were also cloned !)

Edit : some cloning software allow not to copy the partition uuid. Use this option if you know what you are doing, because if you remove your source drive, you will not be able to boot your clone disk (os) unless you modify all uefi bios entries to new uuids !
Do not play with bios entries and uuids unless you are familiar with the boot process, easybcd or efibootmgr, bios options !

Thank you for all of that.  To repeat I have already cloned the source drive AND kept both drives connected.  I ended up using EasyBCD a boot configuration app that stores the boot manager on one of the two physical drives, I think the source drive, and presents you with a boot menu GUI or command line as desired, so I can boot to either source or clone drive just fine.  I think maybe I better leave well enough alone as the clone already has the complicated Prepar3D install on it so if the one now on my source drive becomes corrupt I can already boot to the clone drive and use Prepar3D out of that install.