RHEL/Deb Dualboot

[indecipherable]

I've been working on trying to get a RHEL/Deb dualboot server (at work) for some time and have made not much progress. So I thought I would post here to try and get some traction.

I'm working with RHEL 7.5 GA and an in-house Ubuntu distribution. Before I post any technical data (partitions, grub config, etc), can someone recommend some best practice resources for multiboot config?

 

[atanere]

You want to dual boot a server??? Sorry, that seems odd to me considering that Linux servers often run day after day, for months and years, without rebooting at all. Are you just making comparisons between them? Are they using a GUI (which one?) or just CLI?

Anyway, @wizardfromoz is our resident expert on multi-booting, and I'm sure he'll be along shortly with some ideas to help. Our admin @Rob is well versed in CentOS (maybe RHEL too, I don't know), so he may have some helpful advice as well.

Cheers

 

[wizardfromoz]

I would defer to @Rob on this

(Wizard appears in a puff of smoke, and welcomes @indecipherable )

I've been known to run about 80 or more Linux at a time over 3 rigs (currently 60), but no servers, no RHEL, just as a home user.

My backup solution of choice is Timeshift, which runs off rsync, but Timeshift does not operate over a network, where rsync as used by sysadmins can.

If I get to understand the issues involved I may contribute, but otherwise I will sit back and watch and learn.

Good luck

Chris Turner
wizardfromoz

 

[wizardfromoz]

Just a BTW I am interested in the in-house Ubuntu distribution, has that been re-engineered by staff or a contractor, or other?

Wiz

 

[indecipherable]

You want to dual boot a server??? Sorry, that seems odd to me considering that Linux servers often run day after day, for months and years, without rebooting at all. Are you just making comparisons between them? Are they using a GUI (which one?) or just CLI?

Anyway, @wizardfromoz is our resident expert on multi-booting, and I'm sure he'll be along shortly with some ideas to help. Our admin @Rob is well versed in CentOS (maybe RHEL too, I don't know), so he may have some helpful advice as well.

Cheers

Hi atanere,

I wouldn't say that I *want* to configure dual boot, lol. Depending upon on how I count my career, in over 5 years of linux system administration I have never set up a functional dual boot server for a specific reason.

I'm *told* there is a business use case, so take that for granted.

GUI/CLI isn't strictly specified. Assume the only specifications are RHEL and a flavor of Debian which has no user-friendly installer (disk image in .img format--tested functional as single-boot).

Topically, installation of RHEL GA on top of the Debian distro in free disk space results in a bug/crash; and copy of Debian partitions to properly formatted partitions in RHEL free space with some simple EFI and GRUB config does not suffice.

 

[indecipherable]

I would defer to @Rob on this

(Wizard appears in a puff of smoke, and welcomes @indecipherable )

I've been known to run about 80 or more Linux at a time over 3 rigs (currently 60), but no servers, no RHEL, just as a home user.

[output omitted]

Good luck

Chris Turner
wizardfromoz

@wiz -

Sorry for confusing Ubuntu/Debian--as far as I am concerned they're effectively the same OS in the sense of RHEL/CentOS--it's actually Debian-based. The distribution in question is engineered and maintained by one of our internal Linux engineers. Hopefully he'll sort me out. I'm just trying to save him some work before our upcoming meeting ... however I'm not banking on it, I'd still like to try a couple of new things before we review & implement this use case.

Thanks for the welcome and the luck.

Please refer to my response to atenere for general description of use case.

 

[indecipherable]

In my research on this topic I haven't found the One True Guide to implement properly--differing opinions in EFI vice GRUB, boot partition per OS or no--etc etc.

I can sketch my partition scheme as currently configured:
/boot/efi 1g (RHEL)
/boot 1g (RHEL)
swap 32g
/root 50g (RHEL)
/home 300g* (RHEL)
/boot/efi 1g (deb)
/root 50g (deb)

* given as something near to use case specification

In this case I install RHEL first and use gparted to set sdx6 as efi
Use efibootmgr to create EFI boot entries pointing to deb
Create 40_custom using the deb /root/boot grub config (or so)

This gets me in the ballpark:
I get EFI boot entries to select as well as GRUB entries in the RHEL loader to select for the deb distro; however, none function as expected.

 

[wizardfromoz]

Stan I am wondering whether, as well as @Rob , @JasKinasis might be interested in this?

@indecipherable - Jas is a man of many talents with programming and scripting, works in IT for a living and is the guru on Debian and any other number of skills

I am curious about whether there is a need to have a separate /boot/efi for RHEL and the Debian, under homes use, they can share, even with The Windozer.

I have worked Arch-based, Debian-based, RPM-based, Gentoo-based and Slackware all of the same ESP.

Also curious about the 40_custom re "create" or is that just adding to the standard one that ships with eg

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

... and you add to it?

BUT (Wizard and his but are seldom far apart), this is your Thread, not seeking to derail it when you need answers.

Just curious

Wiz

 

[indecipherable]

Stan I am wondering whether, as well as @Rob , @JasKinasis might be interested in this?

@indecipherable - Jas is a man of many talents with programming and scripting, works in IT for a living and is the guru on Debian and any other number of skills

I am curious about whether there is a need to have a separate /boot/efi for RHEL and the Debian, under homes use, they can share, even with The Windozer.

I have worked Arch-based, Debian-based, RPM-based, Gentoo-based and Slackware all of the same ESP.

Also curious about the 40_custom re "create" or is that just adding to the standard one that ships with eg

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

... and you add to it?

BUT (Wizard and his but are seldom far apart), this is your Thread, not seeking to derail it when you need answers.

Just curious

Wiz

@oz - 40_custom is just one of the MANY recommended places I found in research to put additional vmlinuz GRUB entries (and yes, I added to this file in my current config). I also tried with 11_linux and essentially copypasted vmlinuz entries from the deb distro.

I'm also skeptical of the "need" to have more than one /boot/efi - this is just another of the MANY recommended configurations I've found in forums research. Ostensibly there needs to be a way for GRUB to find and differentiate the various .EFI files. (Note: even EFI is not specified as a requirement for the use case, however RHEL provides it by default, and ideally a solution can implement either legacy and/or EFI boot.)

To be clear: I'm /not/ looking for answers here--lol--my initial post was requesting resources, and ostensibly brainstorming is another resource. ^_^ (However a(ny) RHEL + Deb dualboot setup guide(s) would be /an/ answer(s) /and/ a resource(s) relevant to this thread.)

Any and all feedback is appreciated.

 

[wizardfromoz]

I understand, and Ta (pron. "tar", Aussie for thanks) for being patient with me, and elaborating

I'm also skeptical of the "need" to have more than one /boot/efi

From a Home User's perspective, there are Pros and Cons, the answer of which to use is in your priorities, and is individual, or in your case, perhaps, to the Firm's Mission Critical requirements.

If you get a chance, take a look at this Post of mine, to an enthusiastic Member looking to multi-multi-boot.

https://www.linux.org/threads/multi-multi-booting-from-the-ground-up.19871/#post-59068

Of particular relevance is this bit

Back to my Dell - 2TB HDD, 256GB SSD, 16GB RAM, populating very slowly and carefully, with stuff I want, and stuff I can teach with, or learn from. Or both. ESP on the SSD came with Windows, it's shared between the Distros on the SSD and the HDD, and the My Book has its own, so that if needed, I could unplug it, take it up the hallway, and plug it into Elaine's Inspiron. Plug and play.

So with the My Book, by having an individual ESP, contingency requirements are satisfied, in that it is plug and play with several working Distros. This, as an adjunct to Networking or File/Folder sharing solutions.

One of the downsides to having a shared ESP is that under /boot/efi/EFI/ - you can get a number of "false" entries build up over time, which can include

• References to Distros which have failed to complete installing, but got past a certain point, and
• References to Distros that you have since eliminated through avenues such as GParted, but a trace element remains

... and these can occasionally come back and bite you on the bum.

Are you acquainted with the idea, from

...is just one of the MANY recommended places I found in research to put additional vmlinuz GRUB entries...

with the creation of a file eg custom.cfg that resides in /boot/grub/ ?

Effectively, I believe it can do more than traditional 40_custom et al of /etc/grub.d/

Further, you need only create it as Root or Superuser, then reboot, no need to update Grub.

I use it to run 6 - 7 Manjaro side by side, with none of them having Kernel Panics.

Cheers, gotta fly

Wizard