Laying Out Your OS/2 System

By: Walter Metcalf
Dateline: 04/21/99

Continuing our Primer on the Installation and Setup of Warp, this week we look at some of the ways to lay out the operating system and applications.


Much of what I'm about to say is not new, but since this series is primarily for the new user, I'm including it because if you belong in that category, you may not have read it before. In addition I want to be reasonably complete.

  1. Some of the things that affect how you will lay out your new system are:

    1. Number and relative speed of hard drives;

    2. Presence of other operating systems (e.g. Windows 95, Linux);

    3. Amount of free space on your hard drives;

    4. Number of features you want to install.

  2. Decisions you need to make while determining the layout:

    1. Where to place the swap file?

      This is an important subject: the positioning of the swap file can greatly impact the performance of your system.

      1. The ideal place for the swap file is on a dedicated hard drive.

      2. If this is not possible, then conventional wisdom recommends that if your system:

        1. Has more than one physical drive:

          • The swap file be placed on the root directory of the most frequently accessed partition of the least used drive.

        2. Has only one physical drive:

          • The swap file be placed in the root directory of the most active partition.

      3. For a great many systems, the "most active partition" is the one containing OS/2; so try to keep the swapper away from the operating system where possible.

      4. Personally, I prefer to "bend the rules" a bit and put the swap file in a dedicated partition because it makes it much easier to manage the size. It's possible to do so and sacrifice little or no performance. However the choice is yours.

    2. What filesystem should the OS/2 partition be?

      1. FAT

        • FAT is more compatible with other OSes, but at the cost of being more vulnerable to crashes and other problems. If you must use FAT for your OS/2 partition, be extra careful to back it up regularly.

      2. HPFS (High Performance File System)

        • HPFS was designed to be OS/2's native filesystem and is superior to FAT in every way but one: it cannot be readily read and written by other operating systems. I strongly recommend you use it for your OS/2 system and applications unless you there is a definite need to have the data resident on that partition accessible by other OSes.

    3. How do you want to boot up OS/2?

      Your options here depend partly on what others OSes you already have or will have on your system:

      1. Direct

        If your system contains only one operating system, e.g. OS/2, then turning on or reseting your computer will automatically load and start that OS, and no intermediate menu is required.

      2. Dual Boot

        1. This feature allows you to switch between DOS and Warp using the special command, Boot. Dual Boot requires the following:

          • DOS should already be installed in your system as Drive C:, although it is possible to install it later.

          • OS/2 must be installed in the same FAT partition, using the Easy Installation method.

        2. This method is NOT generally recommended as the most effective method of installing OS/2.

      3. Boot Manager

        This is the method best suited for the majority of OS/2 installations. See the article Boot Manager Shootout: IBM Boot Manager  for more information on Boot Manager. Let's look at some sample Boot Manager installations:

        1. Separate DOS and OS/2 partitions:

          Part. # Format Type Drive Ltr Description
          1 Non-DOS
          Boot Manager
          2 FAT C: DOS
          3 HPFS D: OS/2

          • This is a good basic setup.¹ Keeping a DOS partition available is helpful to run those test programs and utilities that will not run under OS/2. Notice, however, that DOS and OS/2 are isolated, in contrast to the dual boot setup. This allows OS/2 to be installed in an HPFS partition.

          • Note that the Boot Manager menu does not display partition 1; only partitions 2 and 3 are displayed.

        2. Include a Maintenance Partition¹

          Part. # Format Type Drive Ltr Description
          1 Non-DOS
          Boot Manager
          2 FAT C: DOS
          3 HPFS D: OS/2
          4 HPFS E: Maintenance

        3. Multiple-drive system with Maintenance Partition¹

          Dr. # Part. # Format Type Drive Ltr Description
          0 1 Non-DOS
          Boot Manager
          0 2 FAT C: DOS
          0 3 HPFS E: Maintenance
          0 4 HPFS F: Swapper
          0 5 HPFS G: Applications
          1 1 HPFS D: OS/2
          1 2 HPFS H: Applications

          For a good treatment of how the drive letters are assigned, see the document Order in Which MS-DOS and Windows Assign Drive Letters.

        4. Multiple C: Drives¹

          Part. # Format Type Drive Ltr Description
          1 Non-DOS
          Boot Manager
          2 FAT C: DOS
          3 FAT C: Windows 95
          4 HPFS D: OS/2

          The two C: drives cannot both be active at once, so the one last booted from is active and the other one is hidden; this cause a problem in that OS/2 does not always "see" the same partition as Drive C:. System Commander Deluxe by V Communications Ltd. can be used to avoid this problem. System Commander Deluxe also contains many features beyond those offered by Boot Manager.

    4. How much space does OS/2 require?

      As you would expect with such a scalable, feature packed operating system, the amount of disk space required by OS/2 depends heavily on which features you choose to install.

      1. A minimum system, in which you deselected all features, would take about 125 MB plus space for the swap file. This requires the Easy Installation method.

      2. A full system would take about 300 MB. plus the swapper. Such a system includes VoiceType and Networking Services.

      3. The size of the swap file is determined by experimentation once the system is running. The more real memory you have, the less you will use your swapper. I suggest you plan for around 20-25 MB and then adjust up or down depending on how much your system uses once it is running.

      4. The OS/2 installation program requires additional space for temporary files, so leave about 30 MB additional space in the install partition.

      5. The above figures are conservative, and do not allow for newer innovations like Java, as well as special device drivers, so don't be stingy with space: give OS/2 lots of extra room.

        Next time: Installation of the OS/2 System

For Further Reading:

Boot Manager Shootout: IBM Boot Manager  © 1998 Walter Metcalf

Order in Which MS-DOS and Windows Assign Drive Letters  © 1999 Microsoft Corporation

¹This diagram is oversimplified for the purposes of illustration. In fact all partitions except 1 and 2 are logical  partitions, and reside in an extended  partition, which is not shown. For more information see the article Partition Tables.

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