I have a Dell Precision 5820 with two (2) of a possible six (6) internal HDs installed. The first came with a factory-installed Ubuntu 16.04 on board. With a Dell-released Radeon graphics card and a Dell product components "freeze" coming before AMD's Radeon drivers were available for the cards, a linux kernel upgrade (from 4.x to 5.x) was necessary... eliminating a notorious "login loop" seen plaguing AMD and NVIDIA system boots. That done, I've started adding Ubuntu 19.04 to the second internal drive. I've read that 19.04 better-integrates the new kernel and supporting graphics drivers.
The first (1TB) internal drive contains three partitions (made and/or verified with the Disks and GPartEd tools): sda1 (EFI System; fat32; boot/esp), sda2 (Basic data; fat32; msfidata); sda3 (ext4; Linux filesystem).
I partitioned the second (1TB) internal drive with the equivalents (w/r/t size, types, labels, and flags) of the first hard drives' sda2 and sda3 partitions: eliminating the equivalent of the first drive's sda1 partition.
The install location for Ubuntu 19.04 is to be on sdb1 (label=OS; type=Basic data; contents=fat32) and the accompanying filesystem area is to be on sdb2 (label=UBUNTU; type=Linux filesystem; contents=ext4).
I have paused at the point where the Ubuntu 19.04 installation asks me where to install the boot loader, as "Device for boot loader installation", with a default location listed as the MBR on sda.
[Note: it might be useful to give a Grub install option for N-boot usage, and thus, to giving confidence to deferring to and selecting the default sda MBR location for the grub (v2.0.2) boot loader "install", which would then modify (rather than "install"), actually auto-modifying that [previous installation of] grub to "see" the added OS, so that it can display that option in its user 'start-up' menu.
I have read that installing a second grub would supersede the use of the first install, with a third install superseding the use of the second, and so on. So, given that a same-location with modification seems logical, I just need to know (rather than presume) that that is the "plan" before facilitating a more complex issue.
In conclusion, even though I've read that Grub only needs to be in the MBR of drive 1, and have read references to having and tweaking it on all boot-option drives, I am wondering if selecting the default sdb1 location will "update" that Grub[-set] to "see" both OSs... without breaking the running Ubuntu 16.04.3 on the first drive.
Thanks in advance, "frank"
Post-note: So, if I understand the correct way to install, is to actually create all three partitions on each drive: sda and sdb each having and EFI System partition so that its OS installation may install its accompanying boot loader. Then, if that is done, will I need to edit the [single] cfg file? Also, do I run the Grub utility at the command-line (uncertain of the exact command) which re-configures [each] Grub to "know about" its matched OS boot option? As a wrapper to that process, will my startup options (that is, which boot loader to empower) be listed at a point before the boot loader is selected? And if my sense of when the options are kicking in is correct, to get to the choice of Grubs, I will click or hold down certain boot keys (e.g., Esc, F12) after the Dell logo screen appears to indicate that UEFI is "in control" of the boot process? Sorry about the lengthiness. I'm hopefully having an :aha" moment which is finally understanding the sequence of processes and where/what options are presented. Am I on or off base?
sudo update-grubto add a new second install to menu. Since both installs are 'ubuntu' in UEFI, you may want to rename one. See mook765's answer & comments: askubuntu.com/questions/617045/…