Booting from different hard drives
Hello, I'm attempting to boot from multiple hard drives, with one hard drive having one installation of RHEL and the second having another. Virtually all of the help online covers dual windows-linux boot, almost nothing covers this.
I thought it would be simple to add a second option to grub.conf and point it at the second disk, but that has not proved to be the case, ala
title Rhel1
hd(0,0)
kernel /vmlinuz-version ro root=/dev/sda3
initrd /initrd-version
title Rhel2
hd(1,0)
kernel /vmlinuz-version ro root=/dev/sdb3
initrd /initrd-version
but it has proven elusive; when attempting to boot the second option grub complains that "file not found"
Any suggestions?
Responses
Guru
10133 points
EDITED/REVISED
Hi Dave
I've made (a long time ago) dual boot systems. While it's been a while since I made a dual-boot Linux/Linux system. I used to run Fedora & Red Hat on the same system for a while.
I assume but can't confirm that you intend to do this with maybe Fedora/Centos/or older version of RHEL -- along with current RHEL 7.4 current, and most likely RHEL 7.4 Workstation, and not server. However, examine this https://ask.fedoraproject.org/en/question/64994/dual-boot-fedora-centos/, (I can't confirm it will or will not help; your initial post doesn't list what versions of non-RHEL Linux & what version of RHEL you're using). I would imagine the most current, but we can't be sure here.
Also, and this bit, while old, might help. If neither of these help, then when you post again here, please add what what kind of machine (laptop/workstation) you're using, and what versions of non-RHEL Linux (Fedora/CentOS/Scientific Linux), and what versions of Red Hat (I'd imagine RHEL 7.4 Workstation). (Imagine you're helping someone and you're looking for details you don't know to help them with). Hopefully you have a good amount of space on your primary drive.
Check out those links, hope something helps there, otherwise, please post back here with some more details and someone ought to chime in.
Kind Regards,
-RJ
Guru
10133 points
Hi David, I don't claim to be perfect, but (last night) after rereading my post, and then yours I realized I went down the wrong path --- so -- I edited my post (last night) to remove windows and make it Linux/Linux boot (again, last night). So the reply you probably saw that had windows was the one you got in email.
Last night I edited my post to attempt to target your initial request (dropping windows, see last paragraph), so check out the reply I edited last night (I put EDITED/REVISED at the top of the post I made).
As of yesterday/last night my reply has no windows involved whatsoever.
Kind Regards,
-RJ
Guru
9710 points
Hi RJ ! :)
There is absolutely no need or reason to "apologize" - you always try and tried your best to help users and nearly all of your advices or suggestions are very useful. I am having quite some knowledge on (multiple) boot problem topics and I have to say David, that you did provide way too little information here ... What is your setup ? GPT or MSDOS partition table ? (U)EFI or Legacy BIOS ? Which partitions on which disk ? Secure Boot enabled or disabled ?
When you have an EFI setup, booting various Linux distributions is not a problem at all, because every system has its own boot loader files which are located in the /boot/EFI/"dist" folder. The biggest problem to solve could be to boot two different Red Hat systems, because both try to install their bootloaders to the /boot/EFI/redhat folder.
Regards,
Christian
Guru
10133 points
updated/revised
Dave it looks like (from your initial reply to this) you're using 2 different versions of Red Hat to dual boot from. What specific versions? That would be useful for those (whoever it might be) helping you here in this volunteer community forum, especially if one of the versions is likely not 7.x. Please see the update I made last night that has no windows involved as well.
Hey Dave, please revisit the revised post (as of last night), Both myself and Christian L. (and others in the forum) will attempt to help with more details.
Kind Regards,
-RJ
updated/revised
Guru
6222 points
Hello David,
Please state which Red Hat releases you try to dual boot. Sometimes editing grub.conf is not enough. Your syntax hints to RHEL 6.9 or older.
Regards,
Jan Gerrit
P.S. trying to mix RHEL 7.y and RHEL 6.x might only work if you first install RHEL 6.x and install RHEL 7.y afterwards. Never tried it.
Guru
10133 points
Yes, I too was wondering how that might play out. In my initial search, I couldn't find instances of someone dual booting RHEL 6.x (could be what he's using) & 7.y However, I had used a dual boot between Fedora and RHEL, but I can't recall which I installed first. I suspect Jan that you're correct and that 6 ought to go first, but I too have never tried it.
Guru
9710 points
Hi Jan Gerrit,
Yes, not the best idea to install two different Red Hat systems on one machine ... David should expect some trouble and even if he gets it done, continuous "patching" jobs have to be done - think of the different kernels which needs (manually) updating the GRUB configuration on BOTH systems after every new kernel (upgrade) installation. :)
Regards,
Christian
Guru
9710 points
Hi David,
There is one problem, you have ONLY ONE BIOS and it doesn't matter how many disks you have in your machine.
So GRUB can detect the different kernels and systems and you have to choose which one to boot from the menu.
But as I said before, after every kernel upgrade of any of the systems you have to update GRUB on each system. :)
Regards,
Christian
Guru
10133 points
HI David,
I haven't had a chance to dig into this - perhaps tonight, but I found this at Red Hat Docs paragraph 33.1.2 that might (hopefully) give some light to the path... edited/added, that link is for rhel7, and won't be useful in your situation
edited/opps - you already said they are both rhel5 The challenges Christian and Jan mentioned previously may be salient, mixture of UEFI (you can probably shut that off in the bios and use legacy grub), and the obvious differences of grub. Jan had asked for which versions, we see one of them is RHEL 5, is the other version of RHEL indeed 7.y or perhaps 6.x?? Just curious. I'm hoping the link to the doc in this post might shed some light to your specific situation. edited/added, that link is for rhel7, and won't be useful in your situation
Kind Regards,
-RJ
Guru
6222 points
Hello David,
Have you considered to backup the installations using e.g. G4L to an external disk drive and install a modern hypervisor like RHEL 7.4 and create a KVM guest for each installation?
This way the user could access both installations at the same time via ssh and not having to reboot each time he/she needs to switch to the other installation.
Regards,
Jan Gerrit
@R Hinton: David stated both disks are RHEL 5, but different kernels
Guru
6222 points
Hello David,
We are all focusing on the way how to do it, let's switch to the error message.
show us the output of fdisk -l /dev/sda and fdisk -l /dev/sdb to see if the partition tables match your grub.conf
Regards,
Jan Gerrit
P.S. @ALL the reply button is a great way to make the discussion unreadable for each of us.
Guru
10133 points
Thanks Jan for the clarity/sanity.
David, to add to what Jan said about KVM, I've used KVM (Kernel Virtualization Machine, an odd name for the native virtualization in Red Hat and other Linux distros) and it might be a viable option to consider to run these RHEL systems on a Linux system, you could have one KVM instance for each, and have both running under virtualization together.
Since they're both RHEL 5 (thanks for that Jan), I believe you can install the first system on the first drive, and when you go to install the second operating system, during the anaconda operating manual setup make sure to point the MBR during the build to the first hard drive... I believe that ought to update the /boot/grub/grub.conf for you - I think this is something I recall from previous dual boot systems in my past. Hopefully I'm remembering correctly. However, KVM virtualization might be useful.
Kind Regards,
-RJ
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