The overhead isn't too much. We have a script in /etc/cron.daily that run
s
the ntpd program once and goes away. If I was concerned about the overhea
d,
I would do this at IPL and once a week since we don't drift more than a
second every year, but our HMC clock is off by 3 seconds. I got the scrip
t
from one of the redbooks but can't remember which one. 

/Tom Kern


On Wed, 21 May 2008 11:41:45 -0600, dave <[EMAIL PROTECTED]> wrote:

>Thanks, Tom, I appreciate it. However, I would prefer not to
>have to run NTP clients in each of the Linux images due to
>the overhead that can produce.
>
>I think the point of confusion here is, at least to me, that
>the z10 technical overview document seems to imply that STP
>will be used to synchronize the time across LPARs and that
>PR/SM will (gradually) update the hardware TOD clock in each
>LAPR of a system and across systems, so that all of the
>hardware clocks are kept in sync. My question is: what
>happens if z/VM is running on one of those LPARs and PR/SM,
>under the covers, keeps updating z/VM's hardware TOD clock?
>
>Or am I completely missing the point here about what STP and
>NTP client features are supposed to provide?
>
>DJ

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