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I installed multiple Linux distros to test them out and learn more about each to see which I like best. I installed two (Ubuntu 18.04 LTS and Mint 19) on a 256 GB SSD (sdc) and four (KDE Neon, Fedora 29, Manjaro Deepin and CentOS 7, in that order) on a 1 TB HDD (sde).

I can see both distros when I boot into the SSD (sdc), and I could see the first three on the HDD (sde) in it's grub menu, but after installing CentOS, booting it and logging in, it locked up on me. I rebooted, but found that I can only see KDE Neon in grub when I boot to the HDD (sde).

I've read a lot about using grub-install, update-grub and update-initramfs, but I'm not sure which option (or combination) would work here. I was able to successfully get rid of a swap partion on the SSD (sdc) using the instrucitons I found here, but I don't know how much of that would help in this situation. I would like to see all six distros in the grub menu of either sdc or sde, if possible, as well as Windows 10 (on sda). Windows boots fine from its separate SDD, so having it in grub isn't a necessity.

DigitalKnight
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2 Answers2

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I've had some good experiences in the past using the "boot repair" disk which facilitates grub fixes\mods: https://help.ubuntu.com/community/Boot-Repair#Getting_Boot-Repair.

Other people have been having problems with Centos multiboots and some people have blamed it on EFI implementations: https://askubuntu.com/questions/506082/ubuntu-grub-menu-after-installing-centos though some people have had this problem even on older, pre-EFI systems: https://askubuntu.com/questions/962838/dual-boot-grub-and-2-hdds. So this seems iffy. It couldn't hurt to look at your BIOS\EFI settings.

When you install multiple distros you "get" the grub from the latest installation, unless you try to make it otherwise. Sometimes you have the option of not automagically installing grub (depending on distro\installer). See also: https://askubuntu.com/questions/503417/how-to-prevent-ubuntu-from-overwriting-grub-bootloader-after-update.

One last thought: Which version of Centos did you install? There are two version of grub, the new grub2 and the older "grub-legacy". I think Centos prior to version 7 used grub-legacy. If you've installed pre-7 Centos, perhaps grub-legacy can't handle your situation as well as grub2. Maybe trying something like reinstalling Ubuntu 18.04 will get you a grub that works. Even if you are on Centos 7 and the grub-legacy business doesn't apply to you, this might be worth trying.

wurtzkurdle
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  • Thanks, I'll look into those options. After I installed Fedora 29 all of the distros appeared in the grub menu, so I think I'll try reinstalling Fedora and see if I get lucky. I was going to reinstall CentOS (it is CentOS 7 18.10, I believe), but if that's a known troublemaker, I'll try Fedora first. – DigitalKnight Mar 14 '19 at 05:26
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When I reinstalled CentOS 7 on sde5, it "found" all five other distros and added them to grub, so all is good now. If I understand correctly, this could change if I update the kernel on any of these distros, but if that happens, I just need to go back to CentOS and do update-grub /dev/sde5. Thanks for the feedback.

DigitalKnight
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