My Linux runs under zVM, not in a stand alone LPAR. So, NTP or STP not required, correct ?
Thanks Joseph Vitale Technology Services Group Mainframe Operating Systems Pershing Plaza 95 Christopher Columbus Drive Floor 14 Jersey City, N.J. 07302 Work 201-395-1509 Cell 917-903-0102 -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Rob van der Heij Sent: Wednesday, March 18, 2015 2:53 PM To: LINUX-390@VM.MARIST.EDU Subject: Re: Network Time Protocol Daemon needed for zLinux? Just a warning: my understanding is that this quote is talking about Linux in LPAR; that z/VM does not virtualize the ETR/STP. For the rest of us: When you have STP steer the LPAR TOD to keep z/VM on time, Linux will inherit the same (UTC) TOD and runs better on time than anything you can do with ntpd. This will cover the leap second in that the TOD appears to slow down for a few hours, to be on time in the morning. On 18 March 2015 at 19:33, John McKown <john.archie.mck...@gmail.com> wrote: > On Wed, Mar 18, 2015 at 10:46 AM, Vitale, Joseph > <joseph.vit...@bnymellon.com> wrote: > > Hello, > > > > Currently not running NTPD under RedHat, is that necessary or does > > zVM > present time adjustment via Sysplex Timer? > > I think this answers that question: > > http://www-01.ibm.com/support/knowledgecenter/linuxonibm/com.ibm.linux > .z.lgdd/lgdd_r_feature_time.html > > <quote> > > ETR- and STP-based clock synchronization > > Your Linux instance might be part of an extended remote copy (XRC) > setup that requires synchronization of the Linux time-of-day (TOD) > clock with a timing network. > > Linux on z Systems supports external time reference (ETR) and system > time protocol (STP) based TOD synchronization. ETR and STP work > independently of one another. If both ETR and STP are enabled, Linux > might use either to synchronize the clock. > > For more information about ETR, see the IBM(r) Redbooks(r) technote at > > www.ibm.com/redbooks/abstracts/tips0217.html > > For information about STP, see > > www.ibm.com/systems/z/advantages/pso/stp.html > > Both ETR and STP support are included in the Linux kernel. No special > build options are required. > > ETR requires at least one ETR unit that is connected to an external > time source. For availability reasons, many installations use a second > ETR unit. The ETR units correspond to two ETR ports on Linux. Always > set both ports online if two ETR units are available. > > Attention: Be sure that a reliable timing signal is available before > enabling clock synchronization. With enabled clock synchronization, > Linux expects regular timing signals and might stop indefinitely to > wait for such signals if it does not receive them. > > Enabling clock synchronization when booting Use kernel parameters to > enable clock synchronization when booting. > Enabling and disabling clock synchronization You can use the sysfs > interfaces of ETR and STP to enable and disable clock synchronization > on a running Linux instance. > > Parent topic: System resources > </quote> > > > > > Thanks > > Joe > > -- > If you sent twitter messages while exploring, are you on a textpedition? > > He's about as useful as a wax frying pan. > > 10 to the 12th power microphones = 1 Megaphone > > Maranatha! <>< > John McKown > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, send > email to lists...@vm.marist.edu with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/ The information contained in this e-mail, and any attachment, is confidential and is intended solely for the use of the intended recipient. 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