Re: [Vserver] My ISP unable to use ntp ; ( - How can I change /etc/localtime with ntp?

From: Herbert Poetzl <herbert_at_13thfloor.at>
Date: Wed 24 May 2006 - 15:03:34 BST
Message-ID: <20060524140334.GB23259@MAIL.13thfloor.at>

On Tue, May 23, 2006 at 03:50:44PM +0200, Robert Michel wrote:
> Salve Herbert!
>
> Herbert Poetzl schrieb am Samstag, den 20. Mai 2006 um 16:40h:
> > > Could I change /etc/localtime with ntp to correct the time myself?
> > > How?
> > >
> > > On the longterm, it would be nice to have a better timesolution
> > > for vservers - the vserver should be able to use ntp and the
> > > host server should be like the Bios clock - only serving
> > > first information at boottime and serving the beat of seconds...
> >
> > well, that might sound appealing at the first glance,
> > but trust me, that's nothing you really want, for
> > several reasons:
> >
> > - the time system inside the kernel is fairly complex,
> > to virtualize it per guest would add significant
> > overhead just for doing time keeping
> >
> > - there is no point in having 'more' than one time
> > base in a single kernel, once it is correct, the
> > entire system will have precise time
>
> There is an important point - a cheap vserver form an ISP
> who doen't care about ntpd after asking him four times....
> (and then he set the time 2 times manualy...) arrrhhhh....

well, those ISPs would probably not enable the
feature to virtualize the time (which would add
a certain overhead) for their 'cheap guests'
so even if we did do that, it would not help
you very much ...

> > > It should be possibel to use the time independent form a
> > > manipulation of the ISP....
> >
> > you can, just install a time deamon which is system
> > independant
>
> How can I do this, so that every normal program
> (postfix, yaws...) get the time form my deamon?

with a preload library (or a modified libc)

> > or add another layer of virtualization
> > if you do not care about the overhead
>
> I do not think that I can do this as normal
> vsersver-user....

sure, just use UML or QEMU inside your guest

> > but IMHO, the real solution to your issues is to
> > kindly ask the ISP to start an ntpd on the host (or
> > on a special time guest) to synchronize that
>
> I know this, I tried this and it's faild.
> The ISP told me two times that they have installed ntpd
> but they correct the time only once... arrrggghhh...

maybe they just need a few hints how to config
ntpd properly, maybe they do not know how that
works (yet) ...

> Ok, how can I run as normal vserver-user (be root
> on my vserver) an own time daemon?

you need to record offset values, but avoid
changing the system clock (not sure there are
daemons who do that already, but for sure it
can be done)

> You don't mean ntpd or chrony who whant to set
> the time of the kernel?

at least not without modifications ...

best,
Herbert

> Greetings
> rob
>
>
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Received on Wed May 24 15:04:12 2006

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