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Using the /3GB Switch

Note: The /3GB switch is not required for all, or even most, users of FME. The /3GB switch will only benefit those who require translations that will not currently run with 2GB of addressable memory.

Thirty-two-bit versions of the Windows operating system can manage a maximum of 4GB of addressable memory. The 4GB is divided into 2GB for user applications and 2GB for kernel processes. This means that any given application is restricted to 2GB of memory.

Beginning with FME 2006 GB, FME takes advantage of a /3GB switch which causes the operating system to divide the available 4GB of memory into 3GB for user applications and 1GB for kernel processes. Many translations that previously failed due to memory limitations will now run successfully when the /3GB switch is used.

Which operating systems support the 3GB Switch?

The /3GB switch is supported on the following operating systems:

Windows 7
Windows Vista
Windows XP Professional
Windows Server 2003
Windows Server 2003, Enterprise Edition
Windows Server 2003, Datacenter Edition
Windows 2000 Advanced Server
Windows 2000 Datacenter Server
Windows NT Server 4.0, Enterprise Edition

The /3GB switch is not supported on Windows 2000 Server.

Which version of FME do I need?

FME 2006 GB and greater.

How do I enable the 3GB Switch for Windows 7 or Windows Vista?

Open the Accessories program group of the Start menu and right-click on Command Prompt.
Click Run as Administrator.
At the command prompt, enter:

bcdedit /set IncreaseUserVa 3072

Restart your computer.

To disable the 3GB switch for Windows 7 or Windows Vista:

Open the Accessories program group of the Start menu and right-click on Command Prompt.
Click Run as Administrator.
At the command prompt, enter:

bcdedit /deletevalue IncreaseUserVa

Restart your computer.

How do I enable the 3GB Switch for other versions of Windows?

Before FME can use the /3GB switch, you will need to edit your system’s boot.ini file.

You can access this file by doing the following:

Open the System Properties dialog. You can access this dialog by either opening Control Panel and selecting System, or by right-clicking on My Computer and selecting properties.
Select the Advanced tab at the top of the System Properties dialog.
Click the Settings button under Startup and Recovery.
Click the Edit button under System startup. Notepad will open with the boot.ini file.

Under [operating systems], there should be a line that ends with /fastdetect. Add /3GB to the end of this line.

The following is an example of a boot.ini file before the /3GB switch has been added:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems] 
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect

When the /3GB switch is added, the above boot.ini file should look like the following:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems] 
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /3GB

You will now need to restart your computer. When your computer has finished rebooting, your translation should be able to finish without running out of memory.

To disable the 3GB switch for other versions of Windows:

Note: It is recommended that you remove the /3GB switch when you don’t require it.

Simply remove the /3GB switch from your boot.ini file and restart your computer.

Will this work on my 64-bit machine?

It doesn't need to! For 64-bit versions of windows, FME can take advantage of 4GB of addressable memory. If you are running FME on a 64-bit version of Windows, no further action is required. Translations that previously failed because of limited memory should now work.