Configuring Windows: Editing the boot.ini file

If the parallel engine is installed on a computer that runs Microsoft Windows Server, Standard or Enterprise edition, edit the boot.ini file to remove the /3GB switch and, if necessary, add the /PAE switch.

Before you begin

Save a copy of the boot.ini file before you make any changes to the file.

About this task

By default, Windows reserves 2 GB of memory for the kernel and 2 GB of memory for user mode programs. When the /3GB switch is specified in the boot.ini file, 3 GB of memory is reserved for user mode programs, and the amount of kernel memory is reduced by 1 GB. This setting results in an insufficient amount of memory for the kernel. To resolve this problem, remove the /3GB switch, if present, from boot.ini file.

In addition, on servers that have more than 4 GB of physical memory installed, specify the /PAE switch in the boot.ini file. The /PAE switch specifies physical address extensions that allow a 32-bit processor to access memory that is above the 4 GB limit.


  1. Click Start > Control Panel > System.
  2. In the System Properties window, click the Advanced tab.
  3. In the Startup and Recovery area, click Settings.
  4. Click Edit to edit the boot.ini file.
  5. Remove the /3GB switch, if present.
  6. On servers that have more than 4 GB of physical memory installed, add the /PAE switch to the boot.ini file.
  7. Save and close the boot.ini file.
  8. Click OK twice, and then close the Control Panel window.

What to do next

Restart Windows to apply the changes.