Re: [chrony-users] Modifying system date and syncing back

[Ed W <lists@xxxxxxxxxxxxxx>]

On 28/04/2014 13:06, Miroslav Lichvar wrote:
> On Sat, Apr 26, 2014 at 10:53:17PM +0530, mallapadi niranjan wrote:
> > we have certain automation testing where we expire certs by moving
> > date,     We currently do move the date back  by date command ,
> >
> > example:
> >
> > chronyc -a offline
> > date -s '1 month'
> > <perform certain actions>
> > date -s '1 month ago'
> > chronyc - a online
> > chronyc -a makestep
> >
> > what i would like to  know is   can we modify the date after making the
> > time source offline  ?
> I wouldn't recommend doing that. Even if you set the time back to
> where it would be it wasn't stepped, and no measurements were made in
> that period, it could still trigger some code in chronyd which tries
> to detect backward clock jumps and invalidate old samples, or upset
> it enough that it would take longer time to recover.
>
> A better approach would be to make chronyd step the clock via the
> manual feature. For example:
>
> chronyc -a 'manual on' (or enable it in chrony.conf)
>
> chronyc -a -m 'offline' 'settime 1 month' 'makestep' 'manual reset'
>
> chronyc -a -m 'settime 1 month ago' 'makestep' 'manual reset' 'online'

What about simply killing Chrony, allowing it to write its various dump 
files to disk

Then mess with the clock as you see fit

Then restart chrony using the option to reload time from the RTC - this 
should be identical to the situation when booting so everything should 
just come up normally?

Ed W

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