[Bug 200648] [NEW] guest machines falls behind time

[Morten Kjeldgaard]

Public bug reported:

Binary package hint: kvm

We have seen that guest machines can fall considerably behind wall clock
time. This is apparently a well know phenomenon with virtual machines,
and is the subject of a VMware whitepaper
(http://www.vmware.com/pdf/vmware_timekeeping.pdf).

In this whitepaper, it is stated that running NTP guest machines is not
a good idea, and it is reasonable to imagine that the NTP server would
go crazy when the clock constantly is lagging.

A better solution is to have a cron script that runs regularly, updating
the time to the value of the host's hardware clock.

We are running with Ubuntu JeOS, where NTP is a required package. For
the above reasons, this is not a good idea. A package containing a time
synchronizing cron script is a much better solution. Ubuntu JeOS should
ship with such a package.

Another solution (?) could be a modification to KVM, so its virtual
clock device would be tied to the host clock.

Details:
Host machine runs Ubuntu server 7.10.
kvm is a locally back-ported hardy package: QEMU PC emulator version 0.9.0-cvs (kvm-59)

** Affects: kvm (Ubuntu)
     Importance: Undecided
         Status: New

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guest machines falls behind time
https://bugs.launchpad.net/bugs/200648
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