Keeping Time with Amazon Time Sync Service

Details worth highlighting.. They recommend chrony over ntpd, which makes particular sense given that chrony is designed to work well on virtual machine. They are doing leap second smearing like Google does internally. They don&#x27;t say anything about what sort of accuracy you can expect but if the clock source is truly local it could be very good.<p>It&#x27;s kinda neat they&#x27;re using a link local address.

Argh! I wish the NTP servers were usable from outside of AWS.<p>Outside of North America and Europe, there aren&#x27;t as many public NTP servers as there should be. For example, according to <a href="http:&#x2F;&#x2F;www.pool.ntp.org&#x2F;zone&#x2F;south-america" rel="nofollow">http:&#x2F;&#x2F;www.pool.ntp.org&#x2F;zone&#x2F;south-america</a>, South America has less than 50 NTP servers.<p>It would be awesome if the large, widely-distributed providers (not just AWS with CloudFront, but also Akami, Cloudflare, etc.) provided public, Stratum-1 NTP servers at their POPs.

I’m amidst digging into getting some gps clock hardware to make sure an open source db we&#x27;re developing at work can work in some interesting situations. (Hit me up if you wanna join the team ;) )<p>High accuracy time is a fascinating domain. It’s this weird mix of general relativity, hardware, and anthropology. Cesium atoms and satellites vs calendars vs astronomy: who wins? :)<p>Point being: more organizations making high accuracy time available to more folks is a good thing!

&gt; uses a fleet of redundant satellite-connected and atomic clocks in each region<p>I am really curious to know what atomic frequency standards they are using. There is something a little suspicious about the wording. I have a feeling they mean &quot;we use GPSDOs&quot; and there are no atomic frequency standards physically located in each regional datacenter.<p>I&#x27;m also a little surprised to see that the remote clock is stratum 4. It would be interesting to see how they are distributing the time between their clocks.<p>If someone from amazon reads this it would be neat if you posted some more details about your setup.

I have been hoping for this for a long time, with Google’s TrueTime system being so unique. Quite a lot more work would have to go into guaranteeing the results all the way into your application, but this is still a great start.

When is Google announcing TrueTime as a service on GCP? I see them doing this really soon since aws has it now

Interesting to know if they have an SLA for this and how it&#x27;s formulated.<p>Time is important and hard. I doubt that customers who really need precise time would walk away from their ghetto solutions with no SLA because when something like this craps out, it&#x27;s almost always a circus.<p>But hey, when time precision and accuracy is a bonus not a requirement for your AWS instance then &#x27;free local NTP server!&#x27;

I&#x27;d be curious to know how this compares to Google&#x27;s (internal ) TrueTime service[1], and if it allows for development of globally consistent but highly available storage systems like Spanner.<p>[1] <a href="https:&#x2F;&#x2F;research.google.com&#x2F;pubs&#x2F;pub45855.html" rel="nofollow">https:&#x2F;&#x2F;research.google.com&#x2F;pubs&#x2F;pub45855.html</a>

Does this actually work? We had horrible issues with time drifting between services in AWS at scale in distributed systems.<p>Something like eg Google Spanner relies on atomic clocks - it&#x27;s a combination of hardware and software that enable the use of wallclock time.

System clock synchronization is a really hard problem but especially important for things like live video stream encoding where the frame timestamps need to correspond to the real wall-clock (within milliseconds) for things like sub-second play-by-play synchronization.

The amount of dog fooding that happens at AWS is impressive - looks like they needed and built this for DynamoDB global tables (assumes clock sync across all regions) and made it available to all instances.

Curious if I’ll be able to replace the NTP servers inside our PCI-compliant environment with this.

Are there SLAs for this out? Can I get TrueTime-style assumptions about my clock skew?

Is it going to be monotonically increasing?

Somewhat meta, but this is a bit ironic of an offering considering the time on their display boards at re:Invent are noticeably out of sync.