[CentOS] NTP and virtual guests

Mon May 28 14:10:43 UTC 2012
Bob Hoffman <bob at bobhoffman.com>

On 5/28/2012 9:59 AM, James B. Byrne wrote:
> On Mon, May 28, 2012 08:50, Reindl Harald wrote:
>>
>> Am 28.05.2012 14:41, schrieb James B. Byrne:
>>> when power returned all of the restored guests were immediately
>>> shutdown by ntp because the time differential between the
>>> restored systems and that of the ntpd sync servers exceeded
>>> the panic threshold.
>> how can ntpd shutdown a guest?
> I have no idea.  Perhaps I misunderstood what the ntpd man page
> referred to as a panic.
>
> If it is not ntpd then I still need to discover some way of ensuring
> that all the KVM guests that were active at the time of a power
> failure automatically come back on line when the KVM host system
> starts up.  I cannot find any reference to how this is done.
>
> Are there any recommended solutions?  These systems are on UPS already
> but the power failure duration exceeded the endurance of the the UPS.
>
I know when ntp changes the time drastically (like ntpdate) my vsftpd 
just commits suicide and dies..
I imagine something like that is going on with the lvm software either 
on the host or the kvm?

I would suggest turning off ntp before long time shut downs...and (ugh) 
manually going through the host and all vms upon turn on and ntpdate 
them, then turn ntp on, then
reboot to make it all come back on?

perhaps a script that turns off ntp, runs ntpdate on host, then on each 
kvm upon reboot?
this sounds rather scary.