(very OT) Ideal partition schemes (history of partitioning)

[Thomas Mueller]

from Polytropon (excerpt):
                        
> On Sun, 30 Aug 2020 22:12:10 +0000, Thomas Mueller wrote:
> > from Polytropon (excerpt):

> > > Most multi-OS settings seem to work best with BIOS + MBR.
> > > Boot selection can either happen using a PF key at system
> > > startup, if it's more than one disk, or you have a separate
> > > software solution, like GRUB or FreeBSD's boot manager, if
> > > all systems are on one and the same disk.

> > How is that?  It seems to me that GPT would be practically
> > the only way for multi-OS.

> I've been running multi-boot system even before GPT existed,
> and so have many others. With MBR and the restriction with
> only up to 4 "DOS primary partitions", it could be a bit
> complicated, but using "DOS extended partitions" and the
> "logical volumes" inside them could help. For example, I
> once had an experimental system with DOS, OS/2, and Linux.
> If I remember correctly, there were 3 primary partitions:
> #1 for GRUB, #2 for DOS, #3 for OS/2; then one extended
> partition where the Linux filesystems were included in.
> Later I removed Linux and installed FreeBSD, using the
> 4th entry as primary partition #4, and inside it, regular
> FreeBSD labels. But that was many years ago, and time had
> some undesired effects on my memory... :-)

I used to run IBM OS/2, from 1.3 to Warp 4, until one single-digit day in April 2001, when the two-hard-drives setup crashed, trashing my data.

After that, I was never again able to boot OS/2 Warp 4 even from the installation diskettes.

I was left with Linux and DR-DOS 7.03.

OS2 and its successors, eComStation followed by ArcaOS (arcanoae.com) have not advanced as much over the years as FreeBSD, NetBSD and Haiku.

ArcaOS still does not support GPT.  ArcaOS uses FreeBSD network (Ethernet) drivers, raising the question of why spend money on ArcaOS when FreeBSD is free and more usable.

> > Grub 2 can be used to select the partition to boot.

> This only works as long as all the operating system
> you want to have on one and the same disk can actually
> be installed in either a MBR or a GPT partition - it
> is of course not possible to mix them. :-)

I have Grub 2 on a Super Grub Disk written to a USB stick (4 GB).

> Using a boot manager (and typically "wasting" one
> paimary partition for it) was the most convenient way
> to multi-boot on MBR. There was another option: Out
> of the 4 primary partitions, exactly one had to be
> marked "active" (i. e., bootable), because the BIOS
> would simply check for the first partition table entry
> that contained an active primary partition, and then
> transfer control to it. If you accidentally had, by
> whatever means made it possible, achieved to mark two
> partitions active, usually the first one was booted.
> The "order of finding" and therefore booting could
> also have an effect on what "drive letters" would be
> designated to the disk partitions, if the booted OS
> could identify (and maybe use) partitions of the other
> non-booted OSes; what was C: to one system became D:
> for another one.
        
> By the way, the FreeBSD boot manager is an exact example
> of how to multi-boot on MBR. It has worked for decades,
> and due to its size, it does not require a primary
> partition for itself or its configuration, as it would
> fit into a regular boot block natively.

I used Lilo as my boot manager in those days, main OS then being Linux Slackware. 

I was able to boot FreeBSD 8.2 from Lilo, as far as I remember.


Tom