XenServer: Date/Time synchronization issues
By default, XenVMs have their clocks synchronized to the XenServer Host that hosts them and will ignore requests to adjust the time made by an ntp daemon if one is running. If you want a XenVM to have an independent clock, log on to its Text Console and issue the command
echo 1 > /proc/sys/xen/independent_wallclock
then run an NTP daemon.
To revert to the default, issue the command
echo 0 > /proc/sys/xen/independent_wallclock
For more setting up an NTP on the XenServer please refer to the below kb article. Refer to the below kb article for “How to set up an NTP Server for a XenServer network”