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I'm planning installing ubuntu gnome to a fresh ssd and setting up a dual booting system with an existing windows 10 install. From what I can tell, windows is installed in legacy bios mode.

I've seen some conflicting advice around whether it would be best to disconnect my windows 10 drive when performing the install, and then restart with the windows 10 drive back in and set up a bootloader (like grub) via the command line.

Is this neccesary, or will ubunutu be smart enough to detect the windows 10 install when I set up from a live usb and set up the dual boot for me?

Thanks for any advice - I appreciate this may be a matter of opinion if both are viable options.

Pete

Peter Daily
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  • It's not necessary, but disconnecting makes it impossible for you to make certain mistakes that might cause Windows deleted. Once Ubuntu is installed, reconnect the Windows HDD, boot Ubuntu, and run sudo update-grub. That should detect Windows, and add it to grub's boot menu. – mikewhatever Sep 30 '16 at 18:31
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    Be sure to partition in advance and use gpt partitioning. If system is UEFI, grub will still install to drive seen as sda which works. But having an ESP so you could install grub to Ubuntu drive is good to have. If you disconnect Windows drive, you may have to re-add UEFI entry for it. Some UEFI find entries after a couple cold boots, others need help. http://askubuntu.com/questions/743095/how-to-prepare-a-disk-on-an-efi-based-pc-for-ubuntu – oldfred Sep 30 '16 at 18:38
  • @oldfred - I'm going to be installing ubuntu to a fresh SSD drive - will I still need to partition this first? edited second query as answered below – Peter Daily Sep 30 '16 at 18:42
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    If you understand partitions or want anything different than the default / & swap, then you have to partition in advance. Even with BIOS boot gpt has some advantages, but requires a bios_grub partition for BIOS boot and/or an ESP or UEFI boot. I always add both even before I had UEFI system, so I could easily move drive to new system or for changing boot if desired later. If you install in BIOS/MBR then you have to totally reformat if you want to later boot in a newer UEFI/gpt system. – oldfred Sep 30 '16 at 20:20

2 Answers2

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via the command line.

Anything done from command line regarding bootloaders should be considered as something for an advanced user. When this goes wrong and you can not fix problems related to it you might need to re-install the OS.

I would keep Windows 10 attached to the system and let it install Grub by itself. Normally I would believe it should work perfectly and add both systems to the bootloader. Make sure you boot from a UEFI parition when installing Ubuntu if Windows is set like that too and no hibernating from Windows, no fast rebooting.

Thing to look out for is to NOT delete Windows while partitioning. So create unallocated space from Windows with partition magic (for instance), pick "use unallocated space" when installing or "something else" and pick the unallocated space.

Any problems are more likely to be Ubuntu related, and not affecting your Windows, than anything else.

Rinzwind
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  • OP told Win is installed in legacy-mode. – mook765 Sep 30 '16 at 18:37
  • Thanks for this advice. Its good to know ubuntu should take care of this via the standard install. msinfo32 reports that Bios Mode is legacy. Is there anything I should be doing to disable hibernating and fast booting, or are these things that aren't possible in legacy mode anyway? – Peter Daily Sep 30 '16 at 18:39
  • @mook765 ah missed that. – Rinzwind Sep 30 '16 at 18:40
  • @PeterDaily use legacy mode for Ubuntu too (microsoft forced that you need to use the same system on other OSes) – Rinzwind Sep 30 '16 at 18:41
  • @Rinzwind - thanks, I do recall reading that should install ubuntu in the same mode as windows OS. Will I need to do anything special to get ubuntu to install legacy mode, or will it do this automatically? - edit - I think this has now been answered above. thnx – Peter Daily Sep 30 '16 at 18:43
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Just install Ubuntu in legacy-mode to the fresh SSD and install Grub to the MBR of the same drive. When rebooting after install enter BIOS and change boot-order to SSD with Ubuntu in first place, so the system will boot to Grub and you can choose OS to boot. The Windows-drive will be untouched and the Windows-bootloader will not be overwritten. You don't need to detach the Windows-drive to do that.

If you detach the Windows-drive during installation Grub can not find Windows during installation, but you can add the Grub-menu-entry for Windows after reattaching the Windows-drive. Just boot to Ubuntu, open terminal with Ctrl+Alt+T and run command

sudo update-grub

Note:

Make sure Windows is installed in legacy-mode. If Windows is installed in UEFI-mode you have to install in UEFI-mode too. Always install in the same mode. How you boot the installer is how it installs. If you boot installer in legacy-mode, Ubuntu will be installed in legacy-mode. If you boot in UEFI-mode, Ubuntu will be installed in UEFI-mode.

In both modes you don't need to disconnect the Windows-drive. Just take care not to overwite the Windows-partitions during install. Choose Something else after starting installer and create the needed partitions on the fresh drive in the next steps.

mook765
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