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Verify the health of the ESX host operating system


  • The ESX host seems slow
  • There are a lot of errors in the log files
  • Accessing the ESX host over a SSH session is slow
  • Operations performed on the ESX host time out


There are many ways to look at ESX host performance. This article focuses on quick assessment of the 4 main resources:
  • Disk Space
  • CPU
  • Memory
  • Network


There are four major areas to check the health of the ESX Operating System: Disk, CPU, Memory and Network. Each area is discussed in depth in the sections below:
Disk Space

To ensure disk space is not causing ESX operating system problems:

  1. Verify if the ESX host has enough space in the disk. For more information, see Investigating disk space on an ESX host (1003564) .
  1. Verify the CPU resources are not overcommitted and all virtual machines running in the ESX host are not CPU intensive.
  2. Determine if the physical processor is functioning correctly. For more information, see Ensuring your hardware is functioning correctly (1003690) .
  1. Verify if enough memory is allocated to the ESX Service Console. For more information, see Increasing the amount of RAM assigned to the ESX Server service console (1003501) .
  2. Determine if the physical memory of the ESX host is functioning correctly. For more information, see Testing the Physical Memory of the Host or Console Hardware (831) .
  3. Do not run all memory intensive virtual machines in one ESX host because it leads to memory overcommit and decreased performance of the host. Refer the White Paper on "Performance Best Practices and Benchmarking Guidelines"  for more information.
  1. Verify the network configuration on the Service Console. For more information see, Verifying ESX Server host networking configuration on the service console (1003796) .
  2. Verifying network performance issues with ESX. For more information see, Network performance issues (1004087).

    Based on VMware KB 1004019

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