Thanks for sharing the experience. > There are other, better ntpd implementations like chrony which can be configured to never step time. I totally agree that

Thanks for sharing the experience. > There are other, better ntpd implementations like chrony which can be configured to never step time. I totally agree that ntpd is worse, it has an aging code base with many potential security issues, chrony is a better and cleaner implementation. Nevertheless, I refuse to refer to "ntpd" as a worse implementation because it implemented the leap-second as the standard specified. Also, ntpd can be manually configured to never slew time (excluding leap second) if -x and -g are used. > ntpd's behavior of non-monotonic time adjustments was brought to my attention after a developer uncovered database corruption. BTW, my original topic here is how a negative leap second may cause service disruption, ntpd's behavior is only a footnote to that discussion. I think your experience only strengthened my original argument: if the standard leap second implementation (instead of smearing) is used, which is the case in a default configuration, something might happen. But I'm not sure, a negative leap second doesn't break the monotonic assumption. So it's all speculations...