Hello LQ users. I am on a multi-boot pc with 6-HDD (legacy mode):

- Default boot (sda1/sda3, double boot win10/Fedora 30);
- FC32 installed on sdb (/boot on sdb1);
- sdc has FC28 installed; sdd has no system installed; sde has Scientic linux

The grub2 menu allows normal booting from sda3/sda1 (FC30/Win10). The
issue is that FC32 cannot be booted. The grub2 menu points to the wrong partition (/) sdb3 instead of (/boot) sdb1. gparted and fdisk confirm sdb1 is the boot partition.

Installing/reinstalling FC30 and/or FC32 does not make any change in the grub2 menu. Consistently, when runing grub2-mkconfig, the os-prober returns an error on sdb3. Cautious but non expert tentative to simply manually edit grub.cfg did not solve the issue.

During re-install, anaconda does not or cannot update the boot loader; on live system, grub2-mkconfig does not detect/load the right partition for FC32.

Thanks for any advice.

Hi, mlaget,

FC28, FC30, FC32, Scientific Linux, and of all things, Windoze 10? You can do this if you really want to, but you're not making life easy for yourself. You have to do this from one /boot partition. That means 4 kernels, 4 initrds, 4 System.map files, & 4 kernel config files.

If you want my advice, take your empty disk and make it a backup for your data. Then remove FC29 & FC30. Why bother when you have FC32? They'll be obsolete first anyhow. The file that sets what boots is /boot/grub/menu.lst and it doesn't need all that palaver and space-wasting the distros put in. Open it, and search for the term 'menuentry'; the next line should begin with followed by the root drive, and the next has the initrd. Fix the one for FC32.

A better way to get to know stuff is with VMs. You can install new systems as a Guest in your normal system. With that many choices you'll spend half of your time rebooting anyhow. And you'll never get to know anything.

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Thank you Business_kid for your reply and suggestions. I do realize the complexity.
For years i have been using such a mounting or equivalent without problem.

- I make ample use of a professional software which usually compiles and installs itself
on Fedoras. It does not anymore on FC31 or FC32. Therefore i keep FC30 (ssd_0; default boot)
to use it with the scripts/codes i developed over the years. To keep up with Fedora 32
i have it installed on ssd_1 which turns out not to be accessable since grub2 is somehow locked
to point at sdb3 instead of sdb1. This is the real issue i was not able to get
rid of.

- The four other disks which contain various developments are on the
primary and secondary IDEs. Easy to unplug, successive booting with only the two ssds
did not provide any change. Grub2 sticks to pointing to the wrong partition.
Same for running grub2-mkconfig.

- I do not have anymore the menu.lst in /boot you mention. I rather tryied to
manually change sdb3 to sdb1 and modify the UUID accordingly in /boot/grub2/grub.cfg.
No success.

Note: the recommended procedure given in the FC26 administrator guide for resetting
and reinstalling grub2 did not succeded for me (ie; rm /etc/grub.d/* && rm /etc/sysconfig/grub
and grub2-mkconfig -o /boot/grub2/grub.cfg). The latter returned grub2-mkconfig unknown.

I am now considering a corrupted or locked sdb1 ssd partition. we'll see what come next.

menu.lst was a legacy GRUB thing. GRUB2 uses a configuration file written in GRUB's shell language, and the shell module reads it at boot time and generates a visible menu.

It is possible to write this config file by hand, if the scripts give wrong results, though the GRUB team don't encourage this. There's a section in Linux From Scratch on how to do it.

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I've been doing it that way for years. I keep a copy or two of my grub.cfg on hand if it gets overwritten. I don't spend much time looking at my grub menu. I know where I'm headed when I boot up. I also edit update-grub:, to stop writing a new grub file.

Thank you, hazel. Yes, menu list is gone 10+years but I still have it hardwired in.

Use /boot/grub/grub.cfg

what was the error?
Iafter editing the grub.cfg at the next reboot, did you press e for edit to check that the changes took place for the grub menu entry that you changed?
sometimes grub2 won't pick up a separate boot partition and will need to create a menu entry in /etc/grub.d/40_custom, then rerun grub2-mkconfig

Thank you color Purple for your point. I did not check whether the changes
were effective after a direct editing of grub.cfg.

I suspect grub.cfg is produced at every boot following the grub.d directives which suggests
the direct editing is not permanent and requires a change via 40_custom as you indicate.

I'll try the next coming days.

Whenever grub2-mkconfig is run any changes to the grub.cfg will be lost, which normally happens with kernel update.

Interesting to know, thank you.

Re-installing FC32 on its disk as i did twice (one using anaconda, one using blivet to re-declare the existing partitions) the new kernel should have updated grub2. May be a fresh install with re-partitioning a formated disk is required to force grub2 to a new version.