Bob is right, with one caveat: Without the timer, you're dependent on the wristwatch of the operator or CE at the time the system is powered up, and the internal clock does drift a little over time. If you want/need to keep your zOS system exactly in sync with the rest of the world, you need a timer even if you only have one CPU. There's no ntp equivalent for that OS. The timer is extremely accurate, and can be set to periodically sync up with NIST, or some external time reference.
If you're running Linux though, with or without VM, you can skip the timer and just use NTP. Just remember that the Linux clock is set to the system clock at IPL time. If the system clock is off, and your ntp initialization script doesn't issue "ntpdate" to a valid server to set it before starting the daemon, ntp will SLOOWWWLLLYYY adjust the clock till it's in sync. So your clock might not be exactly right for a while after IPL. This is only really important for systems that deal with time sensitive transactions, or compulsives like me. :) > -----Original Message----- > From: Robert Morrison [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, January 15, 2003 2:32 PM > To: [EMAIL PROTECTED] > Subject: Re: [LINUX-390] 2074 and the HMC > > > The Sysplex timer provides a very high speed time reference > that is needed to keep the structures in the Coupling > Facility in jive as well as being extremely reliable. > > The timer is needed if you are going to couple two or more > separate (zSeries / 390) processors together in a Parallel Sysplex. > > You should not need one if you run your OS/390 - zOS images > standalone within a single frame. The clock in the processor > will work just fine. > > Bob Morrison > > > > > > > > > > --------------------------------- > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now >
