On Tue, 4 Dec 2007 15:53:15 +0100, R.S. wrote:
>Itschak Mugzach wrote:
>> So. How Oracle, UDB and other products deal with that "time changing back"
>> on other platforms?
>
>Definition of communism: a system which is fighting to solve the problem
>which are never occured elsewhere. <g>
>
Over a decade ago, IIRC, before the PCs took over our corporate
desktops, I had a SPARC desktop system, and now my MacBook, with
the adjtime(2) function:
Linkname: Mac OS X Developer Tools Manual Page For adjtime(2)
URL:
http://developer.apple.com/documentation/Darwin/Reference/ManPages/man2/adjtime.2.html
DESCRIPTION
Adjtime() makes small adjustments to the system time, as returned by
gettimeofday(2), advancing or retarding it by the time specified by the
timeval delta. If delta is negative, the clock is slowed down by incre-
menting it more slowly than normal until the correction is complete. If
delta is positive, a larger increment than normal is used. The skew used
to perform the correction is generally a fraction of one percent. Thus,
the time is always a monotonically increasing function.
Old technology: the problem may have occurred elsewhere, but it has
been solved in many places. FSVO "generally"; on the SPARC I found
the skew to be about 25%
>Ragrding to original question: in order to have z/OS as a *client* of
>NTP/SNTP/whatever_name you still need to buy STP (or Sysplex Timer) and
>connect it to time server. STP means many thousands dollars.
>
STP does about what adjtime does. Of course, it's all digital, with
increment and offset registers. And z/Series faces the additional
complexity of multiple clocks on multiple CPUs which must be kept
perfectly synchronized. But, all told, the prices I've heard would
seem driven more by customer need and lack of an alternative than by
supplier costs.
-- gil
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