Dual boot ubuntu and rocky 9


i am planing to install ubuntu 22.04 with rocky 9 on same harddrive
i tried to find any article to guide before install them but i get exclusive article from rh What is the procedure to dual boot a server with Red Hat Enterprise Linux ? - Red Hat Customer Portal which i can not access

so what the consideration i should take to make it work

  1. using intel cpu and old bios system
  2. which os should be installed first so it detect the second detect the first one automaticaly and update the grup
  3. is there any recommendation about hard drive layout ?

thanks for your time and have a nice day :slight_smile:

I think both of them give the option to install without a boot loader. Install either one first, then install the second one but don’t install a boot loader. Or install it with the boot loader and it should see the previously installed O/S and add a grub entry for it.
I’d install Ubuntu second, because I remember from experience that it gives an option to share with what is already there.

It’s usually pretty simple. You don’t mention if it’s UEFI or not, but in any case, I think you’re better off installing Ubuntu second. There’s all sorts of articles on the web about booting Ubuntu with another version of Linux. Just make sure when you install that you leave space for the second operating system, that is, don’t fill the disk with Rocky, and then try to shrink it to make room. It can be done but it often causes data loss.

By the way you can create a free RedHat account and get access to their articles.

thanks @scottro

it old bios legacy

i have free account there but it did not allow me to read it as it mentioned
Subscriber exclusive content

thanks again and have a nice day :slight_smile:

Actually, it being legacy makes more simple. I would install Rocky first, leaving room for Ubuntu, then Ubuntu should be able to take care of adding Rocky to grub. You may find, that when you update Rocky, it starts bootiing to Rocky’s grub, but Rocky’s grub should see Ubuntu. This back and forth may go on whenever you update one or the other, so you might want to keep a live USB on hand. I just did a quick web search for dual boot ubuntu redhat and there were several hits, not all from redhat access so a web search will probably find you a good tutorial.

thanks a lot @scottro

I’d expect UEFI to be simpler to maintain.

In legacy the stage0 of GRUB is in sector 0 of a drive. You can have more than one only if you have more than one drive (and you would select what to boot in BIOS).

In UEFI each vendor has its own subdir within ESP. (Only same vendor duals, like Rocky 8 and Rocky 9 would overlap). Each vendor has its very own bootloader and config. Furthermore, GPT does not quickly run out of primary partitions like MBR does – each OS can have its own /boot.

In both modes you can add “the other” to menu of each as chainload.

thanks @jlehtone will keep that in mind and have a nice day :slight_smile: