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4.6. Time handling in Linux VMs

By default, the clocks in a Linux VM are synchronized to the clock running on the control domain, and cannot be independently changed. This mode is a convenient default, since only the control domain needs to be running the NTP service to keep accurate time across all VMs. Upon installation of a new Linux VM, make sure you change the time-zone from the default UTC to your local value (see Section 4.8, “Release Notes” for specific distribution instructions).

Individual Linux VMs can be set to maintain independent times

  1. From a root prompt on the VM, type the command: echo 1 > /proc/sys/xen/independent_wallclock

  2. This can be persisted across reboots by changing the /etc/sysctl.conf configuration file and adding:

    # Set independent wall clock time
    xen.independent_wallclock=1
    
  3. As a third alternative, the independent_wallclock=1 may also be passed as a boot parameter to the VM.