Category: Architecture

Introducing OCC Optimistic concurrency control (OCC) is a time-honored way for multiple writers to safely modify a single object without losing writes. OCC has three nice properties: it will always make progress as long as the underlying store is available, it’s easy to understand, and it’s easy to implement. DynamoDB’s conditional writes make OCC a […]

Internet Routing Internet routing today is handled through the use of a routing protocol known as BGP (Border Gateway Protocol). Individual networks on the Internet are represented as an autonomous system (AS). An autonomous system has a globally unique autonomous system number (ASN) which is allocated by a Regional Internet Registry (RIR), who also handle […]

Choose Your Route Wisely Much like a roadway, the Internet is subject to congestion and blockage that cause slowdowns and at worst prevent packets from arriving at their destination. Like too many cars jamming themselves onto a highway, too much data over a route on the Internet results in slowdowns. Transatlantic cable breaks have much […]

Route 53 Health Checks provide the ability to verify that endpoints are reachable and that HTTP and HTTPS endpoints successfully respond. However, there are many situations where DNS failover would be useful, but TCP, HTTP, and HTTPS health checks alone can’t sufficiently determine the health of the endpoint. In these cases, it’s possible for an […]

Amazon Route 53’s DNS Failover feature allows fast, automatic rerouting at the DNS layer based on the health of some endpoints. Endpoints are actively monitored from multiple locations and both application or connectivity issues can trigger failover. Trust No One One of the goals in designing the DNS Failover feature was making it resilient to […]

In a previous blog post, we talked about using shuffle sharding to get magical fault isolation. Today, we’ll examine a specific use case that Route 53 employs and one of the interesting tradeoffs we decided to make as part of our sharding. Then, we’ll discuss how you can employ some of these concepts in your […]

Deploying new software into production will always carry some amount of risk, and failed deployments (e.g., software bugs, misconfigurations, etc.) will occasionally occur. As a service owner, the goal is to try and reduce the number of these incidents and to limit customer impact when they do occur. One method to reduce potential impact is […]

A standard deck of cards has 52 different playing cards and 2 jokers. If we shuffle a deck thoroughly and deal out a four card hand, there are over 300,000 different hands. Another way to say the same thing is that if we put the cards back, shuffle and deal again, the odds are worse […]

Practically every experienced driver has suffered a flat tire. It’s a real nuisance, you pull over, empty the trunk to get out your spare wheel, jack up the car and replace the puncture before driving yourself to a nearby repair shop. For a car that’s ok, we can tolerate the occasional nuisance, and as drivers […]

At Amazon Web Services we have the great fortune to work on many interesting large-scale distributed systems, as well as the privilege to observe our customers achieve audacious goals. Many highly available services, web sites, and business systems have been built on top of Amazon Web Services. The AWS Architecture blog will dive a little […]