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How to safely Dual Boot on separate drives?

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My specs are:

- Gigabyte Z490 Vision D

- Sapphire Radeon 5700XT

- Intel i7 10700k

- 1x 500GB NVME drive (Windows 10)

- 1x 1TB NVME drive (Big Sur)

- Several other storage drives formatted to ExFat


In the F12 BIOS screen, there doesn't seem to be any distinguishable difference between selecting "OpenCore" or "UEFI OS (WDS100T3XHC-00SJG0)". They both essentially take me to the black screen where I can select "Windows 10" or "Mac OS". However, selecting "Windows 10" from there took me a strange setup page, almost as if I still had to finish Windows installation.


If I selected "Windows Boot Manager (WDS500G3XHC-00SJG0)", it takes me straight to my already smooth running Windows.

I have already got the WDS100T3... as the Boot Option 1, so by default, it takes me to that black screen to select Mac OS. Am I doing this right?


Also, how safe is it to install updates on Windows and Mac?


Thanks in advance!





Edited by KrustyKrab
7 hours ago, BALDY_MAN said:

the last page is booting from your EFI folder on your Mac drive . and its ok to up date windows

sometimes Mac OS updates can give problems

Mac OS updates can cause problems?

How do we stop that from happening or update without issues? Thanks.

2. If you are a linux multi-booter and using grub2 as your main bootloader, and if you have an existing Catalina install with a working chainloaded OC or Clover, suggest you don't disturb/break your existing bootloader by making tweaks for Big Sur.  You can make an additional small 200MB FAT32 partition on your HDD and put your Big Sur bootloader there and chainload it from grub.cfg. Run lsblk -f or sudo blockid from linux terminal and note the UUID of the Big Sur FAT32 bootloader partition you made.  Temporarily edit your boot grub.cfg and add the following entry where xxxx-xxxx is your Big Sur FAT32 bootloader partition UUID:

for open core:


menuentry "Open_Core"{
    insmod part_gpt
    search --no-floppy --set=root --fs-uuid xxxx-xxxx
    chainloader /EFI/OC/OpenCore.efi  # or whatever path you use


or for clover:

menuentry "Clover"{
    insmod part_gpt
    search --no-floppy --set=root --fs-uuid xxxx-xxxx
    chainloader /EFI/CLOVER/CLOVERX64.efi  # or whatever path you use


This way you can easily edit/tweak your Big Sur bootloader settings without breaking your existing working ESP bootloader.  If you are not comfortable using an XML editor to edit config.plist, and you have Catalina installed, you can download ProperTree from github and use it from Catalina.  Later you can modify your linux /etc/grub.d/40_custom to include any custom bootloader menuentries you want to keep, and then run update-grub.
3. When your install is finished and you are finally at the working desktop, you may want to make a backup. With Catalina this was easily done by using Disk Utility from a bootable USB installer to restore to an APFS formatted backup media.  The Big Sur DP4 installer Disk Utility has repeatedly failed to replicate Big Sur and it appears Disk Utility from Catalina 10.15.6 can not perform this task with Big Sur APFS containers. You can, however, clone the entire Big Sur container to removable media with third party software. Alternatively, and depending on the size of your AFPS container/partition and transfer rate, using dd can take quite a long time to do the backup.

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