# clocks

Published articles for clocks.

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## How clock drift and network latency affect distributed database writes, and how Spanner uses TrueTime

DevFeed: [How clock drift and network latency affect distributed database writes, and how Spanner uses TrueTime](<https://devfeed.tech/articles/clock-synchronization-is-a-nightmare-why-spanner-uses-truetime-and-the-rest-of-us-suffer-39579.md>)

Original publisher: [Read original article](<https://ankit-rana.com/logs/27-clock-synchronization-truetime/>)

Author: hello@ankit-rana.com

Published: 2026-05-17T00:00:00Z

Content type: article

Language: en

Sources: [Ankit Rana | Mechanical Sympathy](<https://devfeed.tech/sources/ankit-rana-mechanical-sympathy.md>)

Topics: [distributed-systems](<https://devfeed.tech/topics/distributed-systems.md>), [Databases](<https://devfeed.tech/topics/databases.md>), [Network](<https://devfeed.tech/topics/network.md>), [Latency](<https://devfeed.tech/topics/latency.md>), [Hardware](<https://devfeed.tech/topics/hardware.md>), [Google](<https://devfeed.tech/topics/google.md>)

Tags: [clocks](<https://devfeed.tech/tags/clocks.md>), [consistency](<https://devfeed.tech/tags/consistency.md>), [data](<https://devfeed.tech/tags/data.md>), [databases](<https://devfeed.tech/tags/databases.md>), [distributed-systems](<https://devfeed.tech/tags/distributed-systems.md>), [google](<https://devfeed.tech/tags/google.md>), [gps](<https://devfeed.tech/tags/gps.md>), [hardware](<https://devfeed.tech/tags/hardware.md>), [latency](<https://devfeed.tech/tags/latency.md>), [network](<https://devfeed.tech/tags/network.md>), [ntp](<https://devfeed.tech/tags/ntp.md>), [spanner](<https://devfeed.tech/tags/spanner.md>), [synchronization](<https://devfeed.tech/tags/synchronization.md>), [truetime](<https://devfeed.tech/tags/truetime.md>)

### AI overview

The article explains how quartz-clock drift and variable network latency limit NTP synchronization across servers. It describes how clock skew can cause last-write-wins conflict resolution to silently discard a newer database write, and presents Google Spanner's use of GPS, atomic clocks, and TrueTime uncertainty intervals as a mitigation.

### Source excerpt

Server clocks come from quartz crystals that drift with temperature, and NTP cannot fully correct them because you cannot measure absolute time over a variable-latency network. Under last-write-wins, a node whose clock runs 10 ms fast can silently discard a newer write from a node that is behind: no error, normal logs, lost user data. Spanner solves it with GPS and atomic clocks, where TrueTime returns an uncertainty interval and the commit waits it out.

## What time is it? A simple question with a complex answer. How computers synchronize time

DevFeed: [What time is it? A simple question with a complex answer. How computers synchronize time](<https://devfeed.tech/articles/what-time-is-it-a-simple-question-with-a-complex-answer-how-computers-synchronize-time-27113.md>)

Original publisher: [Read original article](<https://andrea.corbellini.name/2023/01/23/what-time-is-it/>)

Author: andreacorbellini

Published: 2023-01-23T19:15:00Z

Content type: article

Language: en

Sources: [Andrea Corbellini](<https://devfeed.tech/sources/andrea-corbellini.md>)

Topics: [DateTime](<https://devfeed.tech/topics/datetime.md>), [Network](<https://devfeed.tech/topics/network.md>), [Protocol (disambiguation)](<https://devfeed.tech/topics/protocol.md>)

Tags: [clocks](<https://devfeed.tech/tags/clocks.md>), [information-technology](<https://devfeed.tech/tags/information-technology.md>), [network](<https://devfeed.tech/tags/network.md>), [ntp](<https://devfeed.tech/tags/ntp.md>), [performance](<https://devfeed.tech/tags/performance.md>), [protocol](<https://devfeed.tech/tags/protocol.md>), [ptp](<https://devfeed.tech/tags/ptp.md>), [relativity](<https://devfeed.tech/tags/relativity.md>), [standard](<https://devfeed.tech/tags/standard.md>), [time](<https://devfeed.tech/tags/time.md>), [time-synchronization](<https://devfeed.tech/tags/time-synchronization.md>)

### AI overview

This article explains why accurate time synchronization matters for computers, phones, applications, and other devices. It introduces challenges in synchronizing time and examines the Network Time Protocol (NTP) and Precision Time Protocol (PTP), while also discussing concepts including time, change, causality, and the definition of a second.

### Source excerpt

Ever wondered how your computer or your phone displays the current date and time accurately? What keeps all the devices in the world (and in space) in agreement on what time it is? What makes applications that require precise timing possible? In this article, I will explain some of the challenges with time synchronization and explore two of the most popular protocols that devices ...

## The July Galileo Outage: What happened and why

DevFeed: [The July Galileo Outage: What happened and why](<https://devfeed.tech/articles/the-july-galileo-outage-what-happened-and-why-36403.md>)

Original publisher: [Read original article](<https://berthub.eu/articles/posts/galileo-accident/>)

Published: 2019-11-07T08:48:53Z

Content type: article

Language: en

Sources: [Bert Hubert's writings](<https://devfeed.tech/sources/bert-hubert-s-writings.md>)

Topics: [navigation](<https://devfeed.tech/topics/navigation.md>), [systems](<https://devfeed.tech/topics/systems.md>)

Tags: [atomic](<https://devfeed.tech/tags/atomic.md>), [clocks](<https://devfeed.tech/tags/clocks.md>), [gnss](<https://devfeed.tech/tags/gnss.md>), [orbit](<https://devfeed.tech/tags/orbit.md>), [outage](<https://devfeed.tech/tags/outage.md>), [performance](<https://devfeed.tech/tags/performance.md>), [precision](<https://devfeed.tech/tags/precision.md>), [systems](<https://devfeed.tech/tags/systems.md>), [technical-article](<https://devfeed.tech/tags/technical-article.md>), [timing](<https://devfeed.tech/tags/timing.md>)

### AI overview

An excerpt examines the July Galileo outage, explaining how GNSS operation depends on accurately modeling satellite orbits and atomic clocks and distinguishing errors in satellite, clock, and ground timing data.

### Source excerpt

By bert hubert / bert@hubertnet.nl This post is an excerpt of a far longer post on Galileo, its structures and the cause of the outage. Here we'll only focus on the outage - the potential underlying reasons behind it are described in the full article. Since the week-long outage in July I've been fascinated by Galileo and, together with a wonderful crew of developers, experts and receiver operators, have learned so much about what I now know are called 'Global Navigation Satellite Systems' or GNSS.