Applies to: @RISK 5.x and Up

 

Not Enough Memory to Run Simulation When Multiple CPUs Are Enabled

Issue

When running a simulation with Multiple CPU enabled, the Performance Monitor displays the error message “Not enough memory to run simulation”.

Cause

The simulation is unable to allocate the memory it needs to run. In most cases this is not due to insufficient physical RAM, but to limitations in virtual memory or how memory is being used during the simulation.

Resolution

Disk Free Space

Virtual memory uses free space on the hard drive. If available disk space is low, memory allocation may fail.

To fix this, free up disk space on the system drive. You can run the Windows Disk Cleanup tool by clicking Start, selecting Run, typing CLEANMGR, and clicking OK. If you delete files manually, be sure to empty the Recycle Bin.

Smart Sensitivity Analysis

If the Excel model is very large, precedent tracing from Smart Sensitivity Analysis can exceed available memory.

To fix this, open Simulation Settings, go to the Sampling tab, and turn off Smart Sensitivity Analysis. Then rerun the simulation.

32-bit Excel

32-bit Excel is limited to a small memory address space regardless of how much physical RAM is installed. Large simulations may exceed this limit.

A common symptom is that the simulation runs with a small number of iterations but fails with a large number of iterations.

To fix this, install and run 64-bit Excel, which allows access to a much larger memory space.

Summary

This error usually indicates a virtual memory limitation rather than a hardware problem. Freeing disk space, disabling Smart Sensitivity Analysis, or switching to 64-bit Excel typically resolves the issue.

 

 

Related Articles:

Virtual Memory Settings 

Smart Sensitivity Analysis

 Large Address Aware

"Out of memory" Error

Should I Install 64-bit Excel?