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Asking for clarification about:

[1] How can I prevent Windows from overwriting GRUB when using a dual-boot machine

Christopher's answer says: "Windows will overwrite the boot sector whenever you install it, upgrade it to a new version, or use tools like bootrec /fixmbr, bootrec /fixboot, or the older fdisk /mbr. In general, install Windows first, then Linux. The boot sector will stay put until you do one of the things above."

My 6-7-week-old computer (a Lenovo) came with Windows 10 preinstalled and I installed Ubuntu Studio 16.04 in a separate partition. I didn't touch Windows after that until a couple of days ago. Sequence of events:

  1. After finishing in Windows, it was the end of the day, so I shut down. Windows "fast boot" (basically) hibernated the computer instead. I seldom use Windows, so I didn't know about this.

  2. Powering on the next morning, "fast boot" bypassed GRUB and went directly to Windows. I freaked out.

  3. Restarted instead (after learning that this should bypass "fast boot"). Again, into Windows.

  4. Fast-forward... I eventually fixed it with Ubuntu Studio on a USB stick, running boot-repair.

I didn't install or upgrade Windows; nor did I use bootrec or fdisk. But the boot sector definitely didn't stay put.

So... why? And, more important, how to prevent this? I'm guessing that disabling fast boot may be the thing, but that's at best an educated guess. I saw recommendations to disable fast boot in Linux community documentation, but no warnings that fast boot alone could be responsible for killing GRUB.

M4rty
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James Harkins
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    Disabling fastboot has other (needed) benefits. "..Your system can lose data if Windows hibernates and you dual boot into another OS and make changes to files. Even if you do not intend to share filesystems, the EFI System Partition is likely to be damaged on an EFI system. Therefore, you should disable Fast Startup.." from https://wiki.archlinux.org/index.php/Dual_boot_with_Windows – DarkSheep Oct 22 '17 at 00:40

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