Porowski, Ken wrote:
A question just came up from my Information Security dept. about setting
and synching the Mainframe clocks.
We generally reset them whenever we have a full system shutdown and
don't worry about it otherwise but they now want a procedure to
regularly correct clock drift.
Please correct me if I'm wrong
Hardware Clock - Set via HMC/SE to (In my case) GMT/UTC.
Correct
TOD Clock - Set from Hardware clock at LPAR Activation time, not synched
to hardware clock after then.
???
IMHO (I could be wrong), it is synched. It can have offset, it can be
set by T CLOCK, but physically this is same clock engine.
SIMETR - Set from TOD clock by first LPAR referencing it. All other
LPARs with same SIMETR will have same time reference.
SIMETR is for SIMulated ETR. Useful if you want to run sysplex on single
CPC. IMHO it have no meaning in real world.
The only way to 'correct' GMT/UTC clock drift in a plex using SIMETR
would be to Deactivate all LPARs (using the same reference) then
Activate to get new TOD/Hardware reference.
AFAIK yes.
If using an ETR (9037) TOD clocks are continuously (FSVO continuous)
synched to the ETR and a change to the ETR GMT/UTC setting will be
propagated to all referencing LPARs without need for Deactivation/IPL.
Yes. To complement:
If loosing ETR then wait state occur.
That's why two ETRs are recommended.
AFAIK If changing time on ETR console then ...same as above.
--
Radoslaw Skorupka
Lodz, Poland
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