How to keep a VMWare VM's clock in sync?

I have noticed that our VMWare VMs often have the incorrect time on them. No matter how many times I reset the time they keep on desyncing.

Has anyone else noticed this? What do other people do to keep their VM time in sync?

Edit: These are CLI linux VMs btw..

Solution 1:

If your host time is correct, you can set the following .vmx configuration file option to enable periodic synchronization:

tools.syncTime = true

By default, this synchronizes the time every minute. To change the periodic rate, set the following option to the desired synch time in seconds:

tools.syncTime.period = 60

For this to work you need to have VMWare tools installed in your guest OS.

See http://www.vmware.com/pdf/vmware_timekeeping.pdf for more information

Solution 2:

according to VMware's knowledge base, the actual solution depends on the Linux distro and release, in RHEL 5.3 I usually edit /etc/grub.conf and append this parameters to the kernel entry: divider=10 clocksource=acpi_pm

Then enable NTP, disable VMware time synchronization from vmware-toolbox and finally reboot the VM

A complete table with guidelines for each Linux distro can be found here:

TIMEKEEPING BEST PRACTICES FOR LINUX GUESTS http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006427

Solution 3:

I'll answer for Windows guests. If you have VMware Tools installed, then the taskbar's notification area (near the clock) has an icon for VMware Tools. Double-click that and set your options.

If you don't have VMware Tools installed, you can still set the clock's option for internet time to sync with some NTP server. If your physical machine serves the NTP protocol to your guest machines then you can get that done with host-only networking. Otherwise you'll have to let your guests sync with a genuine NTP server out on the internet, for example time.windows.com.