To reiterate Radoslaw's point, STP does not steer the clock. Rather STP steers--synchronizes--the internal clocks of all connected CECs. STP itself may or not be externally steered. In our case, we take an SNTP signal from the corporate time server that is used to synchronize the entire enterprise including Windows, UNIX, and all the other critters in the zoo. If SNTP failed, most everyone would drift apart to some extent, but STP would still keep connected CECs in sync with each other--a basic requirement for parallel sysplex.
. . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 323-715-0595 Mobile 626-302-7535 Office [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of linda golding Sent: Tuesday, April 19, 2016 2:06 AM To: [email protected] Subject: (External):Re: What happens with no working SE? Am curious . This is what i could find looking at the enhancements . Since you say STP doesn't steer the clock , i would like to know how this works these days . *http://www-03.ibm.com/systems/z/advantages/pso/stp/ntp.html <http://www-03.ibm.com/systems/z/advantages/pso/stp/ntp.html>* *Service Element (SE) Time Accuracy* As a continuation of the zEnterprise 196 (z196) timing accuracy improvements for an STP-only CTN, namely, SE/CPC hourly clock steer and synch, the zEnterprise EC12 and zEnterprise BC12 have expanded these enhancements by allowing the SE to access an STP panel-configured External Time Source (ETS), even when the CPC is powered off or has not been IMLed. The SE achieves this by invoking the ETS-configured NTP servers to obtain the ETS-SE time difference and steers the SE clock towards the ETS clock. During IML, the more accurate SE clock time transfers to the CPC clock, maximizing the CPC timing accuracy. This feature is available exclusively on zEnterprise EC12 and zEnterprise BC12. Thanks , Linda On Tue, Apr 19, 2016 at 1:57 PM, R.S. <[email protected]> wrote: > W dniu 2016-04-18 o 23:19, linda golding pisze: > >> One of two SE failed means you can peform everything you want, >> including STP. Maybe STP setup would be impossible (I haven't >> checked), but I'd bet it is also possible. >> I've been working with single SE (primary failed) for some time. It >> wasn't my dream, but I could live with it. >>>> >> >> >> I thought STP code runs on the support element . Access to the NTP >> server from the CTS is initiated and controlled by the Support Element. >> >> In that case , a sysplex would die when support element is not available . >> > NTP is not STP. > STP is managed from HMC/SE but it doesn't mean the SE is steering the > clock. > NTP can be used for "wall clock" time adjustment, but STP will work > without NTP at all or with NTP failure. > Last, but not least: multi-CPC STP configuration will survive any of > the CPC failure. Not only SE, but whole CPC. > > -- > Radoslaw Skorupka > Lodz, Poland ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
