On Wed, 5 Dec 2018 23:02:14 +0100, Carlos E.R. wrote:

> Or, you can just use "bootinfoscript" script, and it will tell you how
> boot is organized.
>
> Download from here and run - in Linux, of course, but a live may do -:
>
> <https://github.com/arvidjaar/bootinfoscript/r...

I haven't posted much as I haven't any new information as it's clear I'm
confused how Grub gets started in the first place, hence the help
is instrumental (where I need to read more of the references).

Hence this post is just the conclusion from that nice bootinfoscript program.

The main thing is, I think, that it cleared up which disk has what:
o HDD3: The only working Windows is on sda (WD10EZEX)
o HDD2: Grub & Ubuntu (17.10) is on sdb (TOSHIBA_HDWD110)
o HDD1: Nothing of use (other than data) is on sdc (WD10EFRX)

Here's how I ran that test.

I connected all three HDDs & booted to Grub which allowed me to boot
to the older Ubuntu (which turns out to be Ubuntu 17.10):
$ lsb_release -a
    Reported Ubuntu 17.10
    <http://www.bild.me/bild.php?file=4360794grub0...

I had originally thought that you just run the bootinfoscript, so while in
Ubuntu, I went to the Windows hierarchy in /media where I had copied
that script (I love that Ubuntu reads Windows partitions!) and ran the
script in Ubuntu - but that's not the way to run the script apparently.
 <http://www.bild.me/bild.php?file=6907397grub0...

You install the boot-info-script program, and then you run the script.
$ sudo apt-get install boot-info-script
$ sudo /usr/sbin/bootinfoscript
    Reported it found sda, sdb, and sdc, putting results in ~/RESULTS.txt
 <http://www.bild.me/bild.php?file=7476838grub1...

The bootinfoscript found Windows on all three HDDs (as expected).
 <http://www.bild.me/bild.php?file=9161369grub1...

======Boot Info Summary: =====
 => Windows 7/8/2012 is installed in the MBR of /dev/sda.
 => Grub2 (v2.00) is installed in the MBR of /dev/sdb and looks at sector 1 of
    the same hard drive for core.img. core.img is at this location and looks
    for (,msdos5)/boot/grub. It also embeds following components:

    modules
    ----------------------------------------------
    fshelp ext2 part_msdos biosdisk
    ----------------------------------------------
 => Windows 7/8/2012 is installed in the MBR of /dev/sdc.

sda1: _____

    File system:       ntfs
    Boot sector type:  Windows 8/2012: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:        /bootmgr /Boot/BCD

sda2: _____

    File system:       ntfs
    Boot sector type:  Windows 8/2012: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:        /Windows/System32/winload.exe

sdb1: _____

    File system:       ntfs
    Boot sector type:  Windows 8/2012: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:        /bootmgr /Boot/BCD

sdb2: _____

    File system:       ntfs
    Boot sector type:  Windows 8/2012: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:        /Windows/System32/winload.exe

sdb3: _____

    File system:       Extended Partition
    Boot sector type:  -
    Boot sector info:

sdb5: _____

    File system:       ext4
    Boot sector type:  -
    Boot sector info:
    Operating System:  Ubuntu 17.10
    Boot files:        /boot/grub/grub.cfg /etc/fstab
                       /boot/grub/i386-pc/core.img

sdc1: _____

    File system:       ntfs
    Boot sector type:  Windows 8/2012: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:        /bootmgr /Boot/BCD

sdc2: _____

    File system:       ntfs
    Boot sector type:  Windows 7/2008: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:        /Windows/System32/winload.exe
... ... ...
 === sdb5: Location of files loaded by Grub: ====
  905.471122742 = 972.242214912  boot/grub/grub.cfg                            
 3
  873.617935181 = 938.040115200  boot/grub/i386-pc/core.img                    
 1
  808.271976471 = 867.875426304  boot/vmlinuz-4.13.0-46-generic
... ... ...
It's clear from the output that Grub is on sdb, but I wasn't sure if
that is the Toshiba or Western Digital HDD so I grep'ed the
RESULTS.txt for "TOSHIBA", which found this section:

=== "ls -l /dev/disk/by-id" output: ===
lrwxrwxrwx 1 root root  9 Dec  6 13:21 ata-TOSHIBA_HDWD110_x -> ../../sdb
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-TOSHIBA_HDWD110_x-part1 ->
../../sdb1
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-TOSHIBA_HDWD110_x-part2 ->
../../sdb2
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-TOSHIBA_HDWD110_x-part3 ->
../../sdb3
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-TOSHIBA_HDWD110_x-part5 -> ../../sdb

Grepping for WDC, I find in the same section:
lrwxrwxrwx 1 root root  9 Dec  6 13:21 ata-WDC_WD10EFRX-x -> ../../sdc
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-WDC_WD10EFRX-x-part1 -> ../../sdc1
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-WDC_WD10EFRX-x-part2 -> ../../sdc2

And...
lrwxrwxrwx 1 root root  9 Dec  6 13:21 ata-WDC_WD10EZEX-x -> ../../sda
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-WDC_WD10EZEX-x-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Dec  6 13:21 ata-WDC_WD10EZEX-x-part2 -> ../../sda2

I can conclude, I think, from the script's output...
o HDD3: The only working Windows is on sda (WD10EZEX)
o HDD2: Grub & Ubuntu (17.10) is on sdb (TOSHIBA_HDWD110)
o HDD1: Nothing of use (other than data) is on sdc (WD10EFRX)

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