VMware 571779-B21 User Guide - Page 8

VMware Tools Configuration Utility User's Guide Configure Time Synchronization Between Guest and Host When you turn on periodic time synchronization, VMware Tools sets the time of the guest operating system to be the same as the time of the host. After that, VMware Tools checks once every minute to determine whether the clocks on the guest and host still match. If not, the clock on the guest is synchronized to match the clock on the host. If the clock on the guest falls behind the clock on the host, VMware Tools moves the clock on the guest forward to match the clock on the host. If the clock on the guest is ahead of that on the host, VMware Tools causes the clock on the guest to run more slowly until the clocks are synchronized. Native time synchronization software, such as Network Time Protocol (NTP) for Linux and the Mac, or Microsoft Windows Time Service (Win32Time) for Windows, is typically more accurate than VMware Tools periodic time synchronization and is therefore preferred. Use only one form of periodic time synchronization in your guests. If you are using native time synchronization software, turn off VMware Tools periodic time synchronization, but do not disable VMware Tools time synchronization completely. Regardless of whether you turn on VMware Tools periodic time synchronization, time synchronization occurs when the VMware Tools daemon is started (such as during a reboot or power on operation), when resuming a virtual machine from a suspend operation, after reverting to a snapshot, and after shrinking a disk. When the operating system starts or reboots, and when you first turn on periodic time synchronization, synchronization can be either forward or backward in time. For other events, synchronization is forward in time. To disable time synchronization completely, you must edit the configuration file (.vmx file) of the virtual machine and set several synchronization properties to FALSE. NOTE Mac guests use NTP and do not become out of sync with the host. For Mac guests, there is no need to turn on VMware Tools time synchronization. Prerequisites Disable other periodic time synchronization mechanisms. For example, some guests might have NTP or Win32Time clock synchronization turned on by default. If you plan to script the commands used in this procedure and need to know what the exit codes are, see "Exit Codes," on page 19. Procedure 1 Open a command prompt or terminal in the guest. 2 Change to the VMware Tools installation directory. Option Windows Linux and Solaris FreeBSD Default Path Change directories to C:\Program Files\VMware\VMware Tools. Change directories to /usr/sbin. Change directories to /usr/local/sbin. 8 VMware, Inc.