[ovirt-users] Time synchronization in guest OS for Hosted Engine VM (for Kerberos)

aleksey.maksimov at it-kb.ru aleksey.maksimov at it-kb.ru
Wed Sep 28 12:16:49 UTC 2016


Robert, you're right. 
Thanks for clarifying.

28.09.2016, 15:10, "Robert Story" <rstory at tislabs.com>:
> On Tue, 27 Sep 2016 13:22:29 -0400 (EDT) Michal wrote:
> MS> > On 27 Sep 2016, at 19:12, aleksey.maksimov at it-kb.ru wrote:
> MS> >
> MS> > I'm afraid that in the future OS time may get out of sync because of kvm-clock
> MS> > And as a result Kerberos may stop working
> MS> > I hope I explained clearly
> MS>
> MS> Sorry, not really. You said you set up ntpd/chrony correctly. So how can the time get out of sync? Why do you think it can be because of kvmclock anyway? Do you refer to some specific bug?
>
> I'd guess that it's a misunderstanding of what kvmclock is. Someone
> guessing based on the name might think that it keeps the vm time in sync
> with the host. Which might lead one to think it would conflict with ntp
> (two different things trying to manage time).
>
> If you know that kvmclock is essentially just a way to monitor the passage
> of time (tick-tock-tick-tock) using the host's timer, then it makes sense
> that you need also need ntp to tweak the current time to adjust for the
> minor drift inherit in any clock.
>
> Robert
>
> --
> Senior Software Engineer @ Parsons



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