[Bug 1462650] Re: Incorrect installation behaviour on multi-drive system

[Phillip Susi]

No -- there is no "pointer to" on disk like you describe with UEFI --
that is how bios works.  With BIOS, it just loads the first sector of
the disk, which then has to locate and load the rest of grub by sector
since there isn't enough room in the MBR for code to parse the
filesystem.  With UEFI, the UEFI firmware locates and loads GRUBX64.EFI
using only an NVRAM variable that tells it to go find that file ( by
name, not location ) to boot something called "ubuntu".

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Title:
  Incorrect installation behaviour on multi-drive system

Status in ubiquity package in Ubuntu:
  Invalid

Bug description:
  I have a PC which has two internal hard drives.  One of them (sda)
  currently has an installation of Mint, and the other (sdb) contained
  an installation of 15.04 at the time of this problem.

  I made a DVD from the testing iso of 15.10 last Wednesday.  On booting
  from this DVD, I was taken to what looked like a grub screen which
  included the option to carry out an OEM installation.  I selected
  'Install Ubuntu'.

  I took the option 'Erase disk and install Ubuntu', and chose sdb as
  the install disk.  At the beginning of the installation, I was given a
  warning notice telling me that the new installation might not be
  compatible with the legacy BIOS installation it had detected on
  another OS (Mint, I assume).  I let the process continue.

  The installer requested that I restart the system and ejected the DVD
  as normal.  On restart, I first allowed the normal grub screen (from
  sda) to appear.  This was my normal, unaltered grub screen, so I then
  re-boooted, and used the BIOS boot menu (entered by pressing the F11
  key on my system) to boot from sdb.  It failed with just a cursor.  It
  seemed to indicate that sdb was not bootable.  I booted from the grub-
  screen into Mint, and used update-grub to make the grub menu pick up
  the Ubuntu installation, which it did.

  At this point, it had not affected sda at all.  I had to update grub
  manually on sda to get into Ubuntu at all.

  The installer seemed to have put grub onto sdb - on a separate boot
  partition.  The grub.config file appeared to be correctly formed.  Why
  it would not boot when I selected sdb, I have no clue at all.

  After that, I installed grub as a legacy bios boot, first onto the
  existing FAT32 partition, and then onto the same partition formatted
  ext4, and finally after deleting the boot partition entirely,
  installing grub to the main system ext partition.  I had no success
  with any of these, except to drop me into an emergency terminal when
  booting from sdb.  The x-server was not available and failed to start
  even manually from the command line.

  When I decided to re-install, everything was the same as before, but
  the warning did not appear at all, and neither did the initial grub
  screen. Grub was installed to sda only, and sdb was not at that time
  made bootable.  I did this manually later.  I didn't understand why
  there should have been any change in behaviour. Happy to answer any
  more questions, I did not make an exact record of any error messages
  first time around as I had assumed that re-installing grub to sdb
  would fix the problem.

  I recorded the exact process on the second installation:
  1) Boot from DVD.
  2) Select 'Install Ubuntu' from the first partition.
  3) Followed defaults after selecting 'Erase disk and install Ubuntu', and selecting sdc as the disk to be erased.

  At no point was there anything to ask where I wanted grub to go.  I
  think this can only be done from the manual install screen.  On the
  second occasion, there was no message about the boot not being
  compatible with legacy BIOS.

  After the requested restart at the end of the installation, grub had
  been installed and updated to sda, and showed Mint, and the two
  installations of Ubuntu (the one on sdb and the one on sdc).  sdc
  itself had not been made bootable.

  That does not explain why it would not boot off sdb the first time,
  but it is may be too late to work that out now.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: ubiquity 2.21.25
  ProcVersionSignature: Ubuntu 3.19.0-20.20-generic 3.19.8
  Uname: Linux 3.19.0-20-generic x86_64
  ApportVersion: 2.17.3-0ubuntu3
  Architecture: amd64
  CasperVersion: 1.360
  CurrentDesktop: Unity
  Date: Sat Jun  6 17:03:49 2015
  InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash ---
  LiveMediaBuild: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150603)
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: ubiquity
  UpgradeStatus: No upgrade log present (probably fresh install)

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