Score:0

Why is Ubuntu 20.04 LTS saying my secondary drive requires mbr?

cn flag

Reading this post Ubuntu won't boot after clean install, I realized I might be experiencing a similar issue with my fresh install of Ubuntu 20.04 on a new hard drive. My primary drive that I installed Ubuntu 20.04 to is /dev/sdb.

But after running boot-repair and the associated boot info, I see a similar log as in the post:

=> No boot loader is installed in the MBR of /dev/sda.
 => Grub2 (v2.00) is installed in the MBR of /dev/sdb...

Do I need to install a boot loader in my secondary backup drive that does not contain the Linux install? If so, why isn't it asking me to install to my primary drive that contains Linux /dev/sdb? Or is/dev/sda always considered primary hard drive? I had to swap out a faulty hard drive.

guiverc avatar
cn flag
Each drive has a MBR (the first 512 bytes of sector of the disk), but each system will only use a single drive to read the MBR from, and it's the machine's firmware settings that control which drive that is. Your question relates to your *unspecified* machine & *firmware* settings, though on many boxes the default saved *firmware settings* can be changed via the use of keys hit before device is turned on or during boot (depends on hardware/firmware!) where as on others that feature can be turned off via firmware setting.. ie. it's box/firmware dependent in my experience
oldfred avatar
cn flag
Boot-Repair is just reporting what is or is not in the MBR. With UEFI systems, now, it is standard to not have any boot loader in MBR as UEFI uses an ESP - efi system partition for initial boot files. Better to post the link from the Summary Report, so we can see all the details. Ubuntu/grub can install in either UEFI or BIOS boot mode to either gpt or MBR partitioned drives. But normally UEFI uses gpt and BIOS uses MBR. With Ubuntu I started to convert drives to gpt with BIOS only system in 2010. The only time you have to have MBR is if you boot Windows in BIOS boot mode.
mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.