On 02/05/2017 11:58 AM, J Martin Rushton wrote: > On 05/02/17 16:15, Richard wrote: >>> Date: Sunday, February 05, 2017 10:26:05 -0500 >>> From: Robert Moskowitz <rgm at htt-consult.com> >>> >>> I have read: >>> http://thegeekdiary.com/centos-rhel-7-chrony-vs-ntp-differences-bet >>> ween-ntpd-and-chronyd/ >>> >>> My server is up all the time and will serve time to internal >>> systems (via DHCP options). >>> >>> Caveat is that my server is an armv7 (Cubieboard2) which does not >>> have an RTC (no battery). So whenever the system boots, the time >>> is ZERO (Dec 31, 1969 or some such). >>> >>> Chrony fixes this really fast; shortly after boot the time is good. >>> Chrony CAN be configed as an internal time server. But chrony does >>> not seem to step the clock for any adjustments needed. It is more >>> important that this systems time be right all the time than to >>> avoid clock steps. >>> >>> This brings me back to NTP, which normally takes hours to bring the >>> time from ZERO to current, but keeps the time correct. >>> >>> So: >>> >>> Can Chrony check the time, say once a day? >>> >>> Or can NTP make a BIG time jump all at once (on system restart)? >> Where I have somewhat similar issues, I have historically used a >> crontab "@reboot" entry to call ntpdate which gets the clock set >> correctly. From there ntp keeps it in sync. >> >> This can now be accomplished with ntpd, and ntpdate is threatened >> with depreciation/retirement. See the top of the ntpdate man page for >> more details. >> > The NTP configuration option you may be after is "tinker panic 0" which > allows NTP to make big jumps as often as required. See ntp_misc(5). > There is a related discussion with making VMs take big jumps at > https://www.centos.org/forums/viewtopic.php?f=16&t=61186&p=258254#p258254 So, if I understand the man page, this command should be the first one in /etc/ntp.conf