Para el caso de que un servidor virtual, cambie su hora, hay que agregar estos parámetros, con la vm apagada :

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1189

Timekeeping best practices for Linux guests

La idea es la de deshabilitar completamente time sync con el host.

“…Select the virtual machine in the VMware Infrastructure Client inventory. On the Summary tab, click Edit Settings, then click the Options tab and select General (under Advanced). Click Configuration Parameters, then click Add Row and add this information:

tools.syncTime = "0"
time.synchronize.continue = "0"
time.synchronize.restore = "0"
time.synchronize.resume.disk = "0"
time.synchronize.shrink = "0"
time.synchronize.tools.startup = "0"