[ntp:questions] Time reset

jkvbe jkvbe at yahoo.com
Fri Apr 4 17:59:28 UTC 2008

On 3 apr, 23:10, "Richard B. Gilbert" <rgilber... at comcast.net> wrote:
> DOES the time step backward?
> If ntpd is working properly it should NOT need to step the time at all
> with the possible exception of a single step when ntpd is first started.
> If ntpd is stepping time regularly, you have some other problem.  If you
> find and fix that problem, ntpd should stop stepping the time.
> There are/were known issues with some Linux systems; during periods of
> high disk usage, clock interrupts would be lost resulting in a FORWARD
> step.  AFAIK these issues were related to EIDE disks used in PIO mode
> rather than DMA mode.  ISTR reading that the problem has been fixed in
> recent versions of Linux.  YMMV

I agree that ntpd should not stepping time regularly and that it
points to a problem if it happens regularly. But we develop an
appliance and we don't control how customers deploy it. Given the
adverse effects of stepping time (especially if it moves backwards),
I'd would have liked to be protected against badly set-up NTP
infrastructure or time servers that are compromised.


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