Boot Manager Shootout: IBM Boot Manager
By: Walter Metcalf
As the conclusion to this loosely-connected series
on hard drives, I want to take a look at some of the boot managers available
and compare them with each other.
The fundamental purpose of boot managers is to provide support for multiple operating
systems on one computer. Regardless of any additional functions they may have, such
as security, they must perform that single function well and in an easy to use manner.
I will be examining three boot managers in this three-part article: Boot
Manager from IBM,
from BlueSky Innovations,
and System Commander
from V Communications.
Review of IBM Boot Manager
As is probably the case with OS/2 users, this was the first boot manager I encountered.
First incorporated into OS/2 in v2.0, it very neatly provides the basic functions
in a totally integrated fashion. In fact it is so well integrated that it is usually
considered simply a feature of OS/2! However for the purposes of this article I
am going to treat it as a separate product.
Along the way I will spend some time discussing boot manager architecture in
general as a foundation for examining the other two boot managers.
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Integrated into OS/2
All boot managers have two parts: one part runs under an operating system and installs
the boot manager code and parameters on to the hard drive. Then second runs this
code at the time the computer is booted.
Unfortunately this automatic, hidden selection of Boot Manager is sometimes a source
of confusion to users new to OS/2 who wish to use Boot Manager but cannot find a
place to select or enable it.
For those who don't already know, selecting the "Advanced Install" option
at the beginning of an OS/2 install procedure automatically enables the installation
of Boot Manager.
The user is given complete control over what kind and how many partitions he/she
wants as well as their size and layout. This is in keeping with OS/2's overall philosophy
of user customizability.
Selecting the "Easy Install" automatically precludes the use of
the Boot Manager during the installation, although it can be added later.
Boot Manager is set up using extensions to the FDISK and FDISKPM programs. (This
is true even during installation, because selecting "Advanced Installation"
causes FDISK to be run.) This is logical for two reasons:
Boot Manager is installed as a special partition; and
All boot managers are intimately involved with the location, type, and number of
The Boot Manager extension is activated simply by pressing <Enter> on a free
space area to install it or on an existing partition to modify its settings, e.g.
to add another operating system to the menu. (In FDISKPM the extension is activated
by clicking on Options in FDiskPM; see screenshot below.)
I won't present a detailed explanation of how to use FDISK, since that is well-documented
in the on-line help and in the OS/2 installation manual. See the IBM Redbooks for
This is not the place to examine Partition Magic in detail. I include it here to
note that PowerQuest
acquired the right to incorporate IBM's Boot Manager into Partition
Magic. (Unfortunately the terms used in Partition Magic are in some cases different
from the one's used by Boot Manager in OS/2, introducing still another element of
confusion into this already confusing topic.)
Completely compatible with hard disk layout specification.
Boot Manager does not disturb any existing structures on the hard drive (e.g. master
boot code). This probably accounts for Boot Manager's remarkable stability and general
"harmlessness." I have used Boot Manager heavily since it was introduced
in 2.0, often with complex setups, and I do not recall a single case where Boot
Manager "bit me" or harmed my data.
Unfortunately this feature has a price: Boot Manager itself requires a primary partition.
As we saw in the previous article in
this series, the master partition table of a physical drive can hold at most four
primary partitions. Owing to the large size of modern hard drives, it's probably
safe to say most OS/2 users have at least one logical drive, which means they have
an extended partition, which is also a primary partition. (If you find this confusing,
I suggest you review the previous article
in this series.) If you also have Boot Manager installed, there goes another primary
partition, leaving only two. DOS and Windows 9x both require primary partitions,
so if you also have both DOS and Windows 9x as I do, you have used all your primary
partitions on your system drive. While four doesn't seem like a lot it is usually
enough, since OS/2 will install in a logical partition, or on another disk drive,
and data partitions almost never require a primary partition. If you look at my
partition setup in the FDISKPM screenshot below, you can see I have filled all four
primary partitions and have four operating systems. If I were to need another primary
partition on that drive, I would need to buy a third-party boot manager. However
most non-Microsoft OS do not require primary partitions or need to be installed
on the first physical drive. So I could probably install such an OS in a logical
partition or a primary partition on my second hard drive. I don't anticipating needing
another boot manager any time soon, if ever.
DOS and all varieties of Windows with the possible exception of NT must be installed
on the C: drive. (Mr. Gates must think he owns drive C:!) This raises a problem
since operating systems do not support two partitions with the same drive letter.
In the screenshot above you'll notice that I have both a straight (MS)DOS partition
and a Windows 95 partition installed. Note that only one of them has the drive letter
C: beside it. The other one is said to be "hidden," and in fact displays
that notation on the Boot Manager menu when my system boots. Either partition may
be selected and booted from. If the Win 95 partition is selected, Boot Manager "renames"
Win 95 as Drive C: and hides the DOS 6.22 partition. The boot process then continues.
According to the Partition Magic 3.0 manual it is possible to hide logical partitions,
but they cannot be booted from.
Partitions may be hidden/unhidden using the FDISK(PM) Options menu, the OS/2 SetBoot
program, and several third-party programs including Partition Magic.
Note: Some of IBM Boot Manager's terminology is different from most of the other
programs and literature, so it should be probably be clarified.
The term Bootable as used in the first screen shot has no equivalent in general
hard disk specifications. In particular it is in no way equivalent to the term "Active."
It simply means that partition is in the Boot Manager menu as displayed when the
computer boots. Nothing more and nothing less. The Bootable status is turned on
by selecting the option "Add to Boot Manager Menu" in the Options menu
below, and turned off by selecting "Remove from Boot Manager Menu."
Note that only the Boot Manager partition has the Startable status. "Startable"
is exactly equivalent to "Active" as used in nearly all other hard disk
literature. Just as there can be only one Active partition there can be only one
Although this was mentioned under the OS/2 Compatibility feature, its importance
warrants listing by itself.
Requires a primary partition
This was discussed earlier under "Compatibility with OS/2" and need not
be elaborated on here.
No security protection
Limited support for number and variety of operating systems.
To some extent this is the result of its complete integration with OS/2 and to
some extent it can be viewed as getting what you pay for: after all Boot Manager
IBM's Boot Manager provides at least the basic functions needed by OS/2 users in
a very smooth, seamless manner. In addition it is quite well documented both in
the online help and the OS/2 manual. In my opinion users should stick with Boot
Manager unless they have a definite need for security or a wide variety and/or number
of operating systems. Other methods require external DOS programs, are considerably
more invasive to the hard drive, and are therefore riskier.
Next week (yes I am returning to weekly articles!) I will look at two commercially
available programs for those whose needs exceed the capabilities of the IBM Boot
For further reading:
Partitions, © 1998 Walter F. Metcalf
Disk Structures and the Boot Process, The PC Guide, © 1997-98 Charles M. Kozierok
an Optimal Multi-OS Environment with PartitionMagic 3.0, © 1998 (?) PowerQuest Corporation