Investigating hosted virtual machine resources

Products

• VMware
• VMware Desktop Hypervisor

Issue/Introduction

This article guides you through the process of determining if a lack of host resources (memory or CPUs) is causing problems with a virtual machine operation. A lack of host resources can cause problems both in a virtual machine's guest operating system and on the host computer where a VMware product is installed and one or more virtual machines are powered on. The steps outlined here help you identify whether a problem is related to insufficient host memory or CPU.

 

Symptoms:
A virtual machine:

• Cannot be powered on.
• Cannot be resumed.
• Cannot be suspended.
• Cannot perform a snapshot operation.

A guest Operating System or a host Operating System with powered on virtual machines:

• Has stopped responding.
• Has performance problems.
• Is slow.
• Is experiencing excessive disk use.

Resolution

To determine if your host has enough resources to support your virtual machines, consider both the amount of memory (RAM) and CPUs.

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Note: The following procedures must all be done when the affected virtual machine is powered off.

 

For each of these resources:

1. Total the amount of the resource assigned to all virtual machines that can be powered on at the same time. If different combinations of virtual machines can be powered on at different times, use the highest total.
   • For more information on checking free host memory, see Investigating operating system memory usage (1004014).
   • For more information on checking free host CPUs, see Investigating operating system CPU usage (1004016).
    
    
2. Add to this the amount of the resource required by your host for its own operations.
    
3. If this total is more than the amount of the resource available on your host, do one of the following:
    
   • Reduce the number of virtual machines powered on at the same time on this host.
   • Reduce the amount of this resource assigned to the virtual machines.
   • Increase the amount of this resource installed on the host.
     
     Note: Alternatively, the host hardware must be upgraded to one with more or faster CPUs.
      

If you have determined that there are sufficient free resources on your host, but are still experiencing a problem with the host operating system or one of the virtual machine's guest operating systems, verify that the operating system itself isn't experiencing a problem. For more information, see Verifying the health of an operating system (1003956).

Additional Information

Virtual machines freeze intermittently or goes unresponsive under heavy I/O load (2088157