![]() ![]() Gamma rays are the highest-energy form of light. Our Sun, occasionally flaring into prominence, serenely traces a path through the sky against the backdrop of high-energy sources within our galaxy and beyond. The cosmos comes alive in an all-sky time-lapse movie made from 14 years of data acquired by NASA’s Fermi Gamma-ray Space Telescope. Watch this video on the NASA Goddard YouTube channel. Music: "Expanding Shell" written and produced by Lars Leonhard.Ĭredit: NASA's Goddard Space Flight Center Fermi Deputy Project Scientist Judy Racusin narrates this movie, which compresses 14 years of gamma-ray observations into 6 minutes.Ĭredit: NASA’s Goddard Space Flight Center and NASA/DOE/LAT Collaboration ![]() : project of virtual cluster of timeserversį info on systemd-timesyncd serviceĪlso see the Ubuntu Time wiki page for more information.14399_Fermi_14Year_Narrated_sub100.mp4 (1920x1080) ġ4399_Fermi_14Year_Narrated_1080.mp4 (1920x1080) ġ4399_Fermi_14Year_Narrated_1080.webm (1920x1080) ġ4399_Fermi_14Year_Narrated_ProRes_3840x2160_2997.mov (3840x2160) ġ4399_Fermi_14Year_Narrated_4k.mp4 (3840x2160) įermi_14Year_Narrated_SRT_Captions.en_US.srt įermi_14Year_Narrated_SRT_Captions.en_US.vtt įermi_14Year_Narrated_Still_print.jpg (1024x576) įermi_14Year_Narrated_Still.jpg (3840x2160) įermi_14Year_Narrated_Still_searchweb.png (320x180) įermi_14Year_Narrated_Still_thm.png (80x40) įrom solar flares to black hole jets: NASA’s Fermi Gamma-ray Space Telescope has produced a unique time-lapse tour of the dynamic high-energy sky. Ntp.org: home of the Network Time Protocol project However, it also implies that on an upgrade from a former release, ntp/ ntpdate might still be installed and therefore renders the new systemd-based services disabled. While use of ntpd is no longer recommended, this also still applies to ntpd being installed to retain any previous behaviour/config that you had through an upgrade. If you require a one-shot time check (without setting the time), use: chronyd -Q.If you require a one-shot sync, use: chronyd -q.But if you had one of a few known special ntpdate use cases, consider the following: timesyncd will generally keep your time in sync, and chrony will help with more complex cases. Ntpdate is now considered deprecated in favor of timedatectl (or chrony) and is no longer installed by default. This ensures that no two time-syncing services can conflict with each other. If chrony is installed, timedatectl steps back to let chrony handle timekeeping. It also stores time updates locally, so that after reboots the time monotonically advances (if applicable). So, on top of the one-shot action that ntpdate provided on boot and network activation, timesyncd now regularly checks and keeps your local time in sync. Timesyncd replaces not only ntpdate, but also the client portion of chrony (formerly ntpd). Since Ubuntu 16.04, timedatectl/ timesyncd (which are part of systemd) replace most of ntpdate/ ntp. Users can also optionally use chrony to serve NTP. See our guide If you would like to know how to configure timedatectl and timesyncd. ![]() ![]() Luckily, all that complexity is hidden from you!īy default, Ubuntu uses timedatectl/ timesyncd to synchronise time, and they are available by default. It must factor in communication delays and adjust the time in a way that does not upset all the other processes that run on the server. The client software is also a lot more complex than you might expect. There are three tiers of NTP servers tier one NTP servers are connected to atomic clocks, while tier two and tier three three servers spread the load of actually handling requests across the Internet. Basically, a client requests the current time from a server, and uses it to set its own clock.īehind this simple description, there is a lot of complexity. Network Time Protocol (NTP) is a networking protocol for synchronising time over a network. Multi-node configuration with Docker-Composeĭistributed Replicated Block Device (DRBD) ![]()
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