Novell SUSE LINUX ENTERPRISE DESKTOP 11 SP1 - 8-18-2010 VIRTUALIZATION WITH ZEN Manual page 111

that need to be synchronized. To effectively use an external time source, such as NTP,
for time synchronization on a virtual machine, the virtual machine's independent wall-
clock setting must be enabled (set to 1). Otherwise, it will continue to synchronize its
time with its host.
Procedure 12.1 Viewing the Independent Wallclock Setting
1 Log in to the virtual machine's operating system as root.
2 In the virtual machine environment, enter
cat /proc/sys/xen/independent_wallclock
• 0 means that the virtual machine is getting its time from the host and is not
using independent wallclock.
• 1 means that the virtual machine is using independent wallclock and manag-
ing its time independently from the host.
Procedure 12.2 Permanently Changing the Independent Wallclock Setting
1 Log in to the virtual machine environment as root.
2 Edit the virtual machine's /etc/sysctl.conf file.
3 Add or change the following entry:
xen.independent_wallclock=1
Enter 1 to enable or 0 to disable the wallclock setting.
4 Save the file and reboot the virtual machine operating system.
While booting, a virtual machine gets its initial clock time from the host. Then,
if the wallclock setting is set to 1 in the sysctl.conf file, it manages its clock
time independently and does not synchronize with the host clock time.
Procedure 12.3 Temporarily Changing the Independent Wallclock Setting
1 Log in to the virtual machine environment as root.
SUSE Linux Virtual Machines 101