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Paul Hoffman
Asked: 2012-03-03 06:43:10 +0800 CST

Best practices for NTP updating in VirtualBox virtual machines without guest additions?

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I have a couple of VMs that cannot have guest additions installed, and I pause and resume them with days between. I normally forget to nudge NTP when I start up the VM. Is there a good way to tell ntp to be very aggressive in how often it should check for changes?

virtualbox ntp

3 Answers

  1. I know you said you couldn't install them, but it's worth saying that the machine additions were created (at least partially) to solve this problem; and should be the solution.

    ntpd can only be set to ignore wild offsets at startup; so you'll have to configure the machines to run ntpdate via cron or similar.

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  2. The Vmware suggested NTP configuration for a similar issue will almost certainly apply here.

    You need to set the tinker panic 0. Make sure your system is not using the local clock as a high stratum server.

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  3. There's also an option to attach ntpdate to network interface up event, which is triggered on guest resume ( man devd for FreeBSD )

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