ML> I think that if you follow the advice of a "guru" who doesn't seem to
 ML> know much about OS/2, you are going to be very disappointed with your
 ML> OS/2 experience.  [...]

 HS>> If you explain this to him, he'll no doubt ask how the heck (and
 HS>> possibly why the heck) you created 4 primary partitions on one drive,
 HS>> since FDISK will refuse to directly do this.  The answer to "how" is
 HS>> that I used my bag of tricks - a combination of FDISK and Norton
 HS>> Utilities.  "Why" is a much longer story.

I think that this is an important point that everybody has missed, and as a
result several people are talking at cross-purposes.

From what he says, it appears that "Linda's guru" has partitioned her disc by
editing the partition table directly, in order to create four type 0X primary
partitions.  (The output of PARTLIST, which I am hoping Linda will post, will
confirm whether or not this is actually the case.)  This is a *very* unusual
setup, and one that is incompatible with several operating systems.  It is
possible to create it using ordinary system tools on some operating systems. 
Windows NT 4's Disk Administrator, for example, allows one to create multiple
primary partitions.  However, when one tries to do so Disk Administrator will
present a large warning message before allowing one to proceed to the effect
that this is incompatible with several operating systems (It actually mentions 
MS-DOS specifically.), and will cause the second and subsequent primary
partitions to be invisible when those operating systems are running.

The conventional setup with multiple primary partitions, for comparison, is to 
have only one of the four primary partitions given an 0X type at any one time, 
and all of the rest given an unrecognisable type (such as 1X), so that whilst
they are recognised as primary partitions, they are skipped by all operating
systems because they don't have a recognised type.  A multiboot utility, such
as IBM's Boot Manager, changes the partition types on the fly so that the
correct primary partition is "visible" (i.e. the operating system will see an
0X type and recognise it) according to which partition is selected from the
boot menu.

My first reaction, as Linda's guru predicted, is to ask "Why?".  As you
rightly pointed out, there is very little reason to do what he has done.  The
normal way to have multiple operating systems on a single drive is to have
three entries in the primary MBR: Boot Manager (a type 0A entry) to allow
booting from any primary *or extended* partition, a single FATxx or type 07
primary partition (which is used to boot all Microsoft operating systems such
as DOS, DOS-Windows 3.x, DOS-Windows 9x, and Windows NT, using the "play
musical chairs with the config files" facility that Microsoft provides in lieu 
of making its operating systems bootable from non-primary partitions), and the 
extended partition (a type 05 or 0F entry).  Operating systems such as OS/2
Warp, linux, and the various PC unices, which don't *need* to have any
presence on a primary partition *at all* in order to boot (in contrast with
DOS, DOS-Windows 3.x, DOS-Windows 9x, and Windows NT), can then be placed in
logical drives in the extended partition.

I fail to see any reason why one would choose to use the scheme that Linda's
guru has had to craft by hand using a partition table editor.  The only
possibility that I can think of is that he is motived by (a) wanting all
operating systems to see all data on the drive and (b) not knowing about Boot
Manager and wants to be able to use the DOS FDISK to switch between partitions 
by changing the "active" flag around.

The former point, that he might want all operating systems to see all data on
the drive, I can understand, because with the "usual" scheme for multiple
primary partitions, as many people have rightly pointed out, the space on the
other three primary partitions is always unusuable, since they aren't
"visible".  This has to be the case, in order for the correct partition to be
recognised as the primary boot partition (and given the same drive letter, C,
where applicable) by *all* operating systems.  But I think that (if this is
the case) he is either unaware, or has forgotten, that not all operating
systems can recognise one another's volume formats *anyway*.  Even if he has
all four primary partitions set to type 0x, for example, the *highly
recommended* setup is for OS/2 Warp to have an HPFS volume for its boot
volume, not FAT.  In which case other operating systems, such as MS/PC/DR-DOS, 
which do not natively understand type 07 partitions at all, will still not be
able to access and use the space.  So he hasn't actually gained what he
wanted.  The same would be true if, for another example, Linda had chosen to
install linux on one of those primary partitions, since DOS cannot understand
EXT2 either.  So I think that the idea that one can keep all space usable by
the mechanism of having multiple "visible" primary partitions simultaneously
is based upon a misconception.

The latter point, that he might want to use the DOS FDISK to multi-boot by
changing the "active" flag around, is countered by the fact that Boot Manager
is a *much* better way of achieving the desired end, of booting from different 
partitions, and one that can be used *without* having to hand-craft such a
non-standard partition table.  Once Boot Manager is installed, *it* is the
active partition, and stays the active partition all of the time.  It then
presents a menu, and allows one to boot from any other partition.  Boot
Manager will arrange to modify the partition types in the primary MBR on the
fly to keep the correct primary partition "visible" if one has more than one
primary partition; but generally one doesn't, since Boot Manager has the very
welcome bonus that it can boot from *any* partition, primary or extended, on
*any* disc that is accessible via the BIOS.  One doesn't actually *need*,
therefore, multiple primary partitions in the first place, since one can place 
OS/2 Warp (or, say, linux) entirely within an extended partition -- on a
secondary or tertiary disc, even -- and have Boot Manager boot it from there.  
This also quite neatly addresses the problem of allowing as much space as
possible to be available at any time, too, since if there is only one primary
partition (for DOS, DOS-Windows 3.x, DOS-Windows 9x, and the boot files for
Windows NT) it is always "visible" and there is no need to have "hidden"
primary partitions that cannot be seen.  The only space that will be
unavailable is the space in volumes whose filesystem types the currently
booted operating system cannot understand.

I'm hoping that Linda's guru will explain the answer to "Why?".

 ¯ JdeBP ®

--- FleetStreet 1.22 NR
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