Multiple Operating Systems

Running More than One OS on a Computer

Notice: The information on this archived page is quite dated and not regularly maintained. Information is preserved for those running older OS/2 systems and for historical reference.

OS/2 & Multi-OSs | Using Boot Manager | Partitioning Your Drive
Useful Multi-OS Tools | Multi-OS Mailing Lists

There is more current multi-OS and dual-boot information in Russ Harvey's Resources Section. The information on this page will primarily of interest to those running OS/2 with other operating systems.

OS/2 in a Multi-OS Environment

OS/2 Warp provides a stable and work-friendly operating system which wins over those of us who take the time to learn its advantages. However, many find that they must use programs either at work or at home for clients that only operate in the Windows 9x/ME or Windows NT/2000/XP environment. Unless you can afford a second computer you need to figure out how to configure the various operating systems so that they will cooperate with each other.

Removable Drive Bays

Since the price of hard drives has come down significantly, you can purchase a removable drive bay that can be easily swapped for your various OSs. Note that you should be sure to purchase the same brand and model of drawer if you wish to leave the hard drives in the bays and ensure that the correct drawer is purchased if you are running ATA66 or better drives.

Sharing With Windows

The challenges of sharing various Windows versions is detailed on this Microsoft 2000 Server Documentation: Installing more than one operating system on your computer (click on the appropriate link in the Notes section). While this resource is Windows-specific it may help you to make appropriate adjustments on your multi-OS setup.

Getting Everything to Co-operate

OS/2 can co-exist with other operating systems, but there are some challenges and tricks to getting everything to co-operate together.

Windows 9x/Me in particular is very fussy (demanding the C: primary partition) and is a predatory operating system that will try to write data into any drive or partition that it can read (FAT16 in particular). It will offer to format anything it cannot read (such as HPFS). This is very destructive to the OS/2 extended attributes, particularly on removable media such as Iomega Zip Drives. Partition Magic running from Windows will also offer to "fix" partitions on a multi-OS system--something that will ruin your OS/2 partitions.

Fortunately the latest fixpaks for Warp 3 and Warp 4 create the ability to format removable media with HPFS, thereby protecting them. Check my removable media page for more information.

Installing OS/2 WARP on a >8.4G HDD preloaded with Microsoft WIN9X by John Twelker is on the V.O.I.C.E. December 1999 on-line newsletter.
Filesystems HOWTO by Martin Hinner documents how to see other file systems (including HPFS and OS/2 LVM) from various operating systems, including NT 4, DOS and Linux.

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Using Boot Manager

Using the Boot Manager that comes with OS/2 you can select from among the various operating systems during the boot process. The ability to boot OS/2 from logical partitions certainly makes this an easier task.

One thing to be aware of is that the OS/2 operating system (but not necessarily OS/2 data files and programs) must be placed on a partition that is completely under the 1023 cylinder limit or you get some strange readings from the OS/2 FDISK. This can be a challenge in today's larger hard drives. If you are installing to an IDE hard drive larger than 4.3GB, you will need to update your Installation Diskettes with the IDEDASD.EXE package following the instructions found on

the OS/2 Device Driver Pak On-Line

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Partitioning Your Hard Drive

One tool that you will find useful in setting up multiple operating systems is an older version of Partition Magic from Power Quest. You can create and modify partitions without destroying the data although you are advised to backup the data in case something does go wrong during the process. Power Quest indicates that the most likely problem would be a power failure at certain critical points in the process.

Unfortunately, native OS/2 support is not offered in Partition Magic releases after version 3. There are instructions on creating a bootable command-line version that runs from DOS or OS/2 rescue disks. Symantec's Partition Magic version 8 doesn't support anything but Windows

You can also transform FAT16 partitions into HPFS without losing the data (but not the reverse). Be warned that OS/2 and Windows 9x don't necessarily see the partition information the same way, but Power Quest offers a method to get them to jive if that is important enough for you. I created my OS/2 partitions with Partition Magic under Win95, then deleted and recreated those same partitions under OS/2.

I found that I could use Partition Magic to create a "hidden" C partition for Win95 then also place OS/2 on another C partition that is visible. This avoided the problem of OS/2 insisting on writing information onto the C drive when it is used by an operating system other than OS/2 itself. The problem comes if you wish to include Windows NT 4 on a logical partition. You can begin the installation process but Windows NT doesn't seem to be able to see that partition upon rebooting the system. I'm not aware if Windows 2000 is able to resolve this issue.

One caveat: You should set up the partitions prior to installing the operating systems since adding or changing the file system can alter the drive lettering as it is viewed by the various operating systems. Operating systems beyond the C: partition might not be able to boot or if they boot may be unable to locate programs on other partitions. In the latter case you would merely have to reinstall the programs to correct the problem. Remember to check your configuration files (CONFIG.SYS and AUTOEXEC.BAT) as well.

You might like to read the challenges for OS/2 users of Partition Magic 4 detailed in Partition Magic 4.0, Revisited on the SCOUG site. You will find some workarounds that aren't found in the official software documentation.

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Useful Tools & Sites For Multi-OS Configurations

Das Boot ("Getting the boot") on the PC Lube & Tuning site will give you some good basic information about how the various operating systems work and how you can get them to work together. It is dated 1995 but still contains lots of useful information.

Multi-OS Software Tools

There are several programs offered for sale that work with multiple operating systems:

One of the oldest is System Commander from V Communications. System Commander allows up to 32 Operating Systems in a DOS partition or each in their own primary or logical partition. You might wish to read the review of System Commander Deluxe by Walter F. Metcalf.
kBootManager is intended as a supplement or replacement for the OS/2 BootManager.
Power Boot is a utility that allows you to install and run multiple operating systems without the restrictions that others like Boot Manager and CtrAltDel Commander impose such as the ability to place an OEM version of software that checks for other operating systems before allowing a new installation (e.g. Windows 9x).
Polarbar Mailer is currently a freeware Java (and therefore multiplatform) e-mail program evolved from the Innoval J-Street Mailer.

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Multi-OS Mailing Lists

OS/2-NT A support & discussion mailing list for folks running WindowsNT and OS/2 Warp. There is also support for Win95 and Win98 with OS/2.

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