Poor Performance When You Use IBM OS/2 Warp As a Guest Operating System

When you install IBM OS/2 Warp as a guest operating system in Virtual PC, you may find that the performance of the guest PC is poor.

To work around this issue, use the following methods to increase the performance of the IBM OS/2 Warp guest operating system.

• When you create the virtual hard disk (.vhd), use a FAT file system instead of a high-performance file system (HPFS).
  
  You can use the Virtual Disk Wizard to control the type, the format, and the size of a virtual hard disk. To start the Virtual Disk Wizard:
  1. Start Virtual PC.
  2. On the File menu, click Virtual Disk Wizard, and then follow the directions that are displayed on the screen.
  3. When you are prompted to select the disk format and size, select either FAT32 or FAT16.
• Increase the OS/2 Warp FAT file system cache.
  
  The FAT file system cache is typically controlled by OS/2 Warp based on the amount of RAM in the computer. However, you can change this setting to increase the performance of OS/2 Warp when you use it as a guest operating system in Virtual PC.
  
  You may find that the following setting is effective:
  DISKCACHE=14400,LW,128
  Note This setting uses 14 megabytes (MB) of RAM for the disk cache. If 14 MB is too high, you may want to reduce the 14400 value to 8096. These are only suggested values. Your results will vary depending on your system configuration.
  
  For more information about how to increase the OS/2 Warp FAT file system cache, see your OS/2 Warp documentation.
• Use the –usehostdiskcache command line switch when you start Virtual PC. To do so:
  1. Click Start, and then click Run.
  2. In the Open box, type "c:\program files\connectix\connectix virtual pc\virtual pc.exe" -usehostdiskcache, and then click OK.
  Note By default, Virtual PC is installed in the "C:\Program Files\Connectix\Connectix Virtual PC" folder. If your installation is different, you must modify the path in this command accordingly.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.