Boot confusion

[Liam Proven]

On Sun, 13 Jun 2021 at 02:43, Jack McGee <jack at greendesk.net> wrote:
>
> I guess my question, is what is best command to copy root filesystem to
> new drives.

I can't give you any official, canonical answer, because there are
multiple different ways of doing such things which have evolved over
the 50 years of *nix history.

In my personal opinion, the easiest way would be to boot the computer
from a live USB key of the latest available released version of Ubuntu
and use the GParted tool to copy the root partition, then resize it
however you want. Then you can copy any other partitions as well.

The following only applies to disks partitioned with the MBR (DOS) scheme.

On MBR you can only have 4 primary partitions. 1 & only 1 can be an
extended partition, and this can contain others, called "secondary" or
"logical" partitions.

Because DOS and Windows must be in a primary partition, marked Active
(Bootable), to boot successfully, but Linux is perfectly happy in a
secondary partition, the way I do it is this:

I have a primary partition with DOS or Windows. Win7/8/10 tend to want
2-3, such as a system partition and maybe an ESP as well. I let them
have up to 3 primaries, but no more. If there are more, e.g. data
partitions or recovery partitions, I copy their contents elsewhere
then delete them.

Then I make an extended partition as the last primary on the drive.
Then inside that, I install as many Linux distros as I want, with 1
secondary root partition each.

After all those, inside the extended partition, then one big shared
/home partition, and last of all, one shared swap partition.  Since
you have a separate drive for /home this may not apply to you.

> I guess I can install grub on that drive after I have moved root filesystem?

Yep. There are lots of how-tos on how to do this.

E.g.

https://help.ubuntu.com/community/Grub2/Installing

https://howtoubuntu.org/how-to-repair-restore-reinstall-grub-2-with-a-ubuntu-live-cd

https://www.howtogeek.com/114884/how-to-repair-grub2-when-ubuntu-wont-boot/

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