On Wednesday, 05/21/2008 at 02:43 EDT, dave <[EMAIL PROTECTED]> wrote: > 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?
As CP perceives time, nothing happens. The clock keeps on ticking. But to the outside observer the ticks will occur faster or slower, depending on whether the LPAR is ahead or behind. No sudden clock movements and no anti-time is introduced (time will not flow backwards). Think of it like slowly turning a screwdriver that adjusts the clock oscillator frequency. The drift is so small that it takes a long time (human scale) for the drift to reach the point at which "steering" is not possible. Only when the machine has no external time reference (e.g. NTP) will the clock drift that far. Only when the h/w is reconnected will STP tell the LPAR (if the opsys has asked to be told) that the time shift is too severe to steer back on course in a reasonable amount of time and that a Quantum Leap has happened. Alan Altmark z/VM Development IBM Endicott
