Problem: ntpd, when installed on a virtual machine running Ubuntu (I've had this on hosts with a variety of hypervisors such as KVM and VMware ESX) seem to be prone to severe clock drift. I haven't found any good method and not everyone seems to experience this.

Question: How can I prevent this? Are there any settings in /etc/ntp.conf to force ntpd to be more aggressive in synchronizing the time inside the VM or should I use ntpdate -b timeserver instead inside a cron job running every so often?

Which method is recommended to avoid leaps when using ntpdate -b or clock drift in general inside a Ubuntu virtual machine?

Side-note: I've seen similar effects on vios (IBM hypervisor) slaves running AIX as well as on Solaris. So the problem is very real and appears to be related to hypervisors in general.