Red Hat Knowledgebase

When running a guest operating system under VMware it is important to follow all of VMware's instructions regarding installation and configuration of the desired operating system as a VMware guest, including installing the VMware Tools package.

Time synchronization problems are a common VMware guest configuration issue which occur when VMware Tools have not been installed on the guest and configured according to VMware's instructions. VMware virtualizes the timer/clock functions seen by the guest OS, so even ntpd does not function correctly. This is not a problem with the operating system, it is a by-product of running the OS under VMware.

To correct the time drift problem seen in the guest OS, install the VMware Tools package in the guest OS and enable time synchronization for the VMware guest session the OS runs under. VMware Tools packages for all current versions of Red Hat Enterprise Linux are provided with the VMware software product, and specific instructions for installing VMware Tools for each type of guest OS is provided in VMware's built-in help menu system as well as in other VMware product documentation.

The following is a brief summary of the steps to enable VMware host-to-guest time synchronization:

• Install VMwareTools in the guest OS, following VMware's instructions for the target OS.


• Enable VMware time synchronization in the guest. There are two simple ways to accomplish this:

  1. Run the vmware-toolbox GUI applet from within an X session on the guest, and turn on the checkbox in the Options tab titled "Time sychronization between the virtual machine and the host operating system".

  2. On the HOST machine, locate the <session name>.vmx VMware session configuration file for the guest OS in question, and add a line which reads:

  tools.syncTime = "TRUE"

  Note that if a tools.syncTime line already exists in the .vmx file, it must be set to "TRUE" to enable the time synchronization.

After making the changes described in either method, shut down the guest Red Hat Enterprise Linux operating system, then close and restart the VMware guest session.

Running the ntpd daemon should not be required in the guest with VMware's time synchronization enabled, though using ntpd on the host system would be recommended to keep the host (and guests') time synchronized to a reliable time source.

Please refer to VMware's support channels for further VMware documentation and support information, such as the VMware website.