To test this new feature, I need a dual-stack application with an ALB entry point. The application must be deployed in Amazon Virtual Private Cloud (Amazon VPC) and support IPv6 traffic.
Protocol translation is not supported, neither IPv4 to IPv6 nor IPv6 to IPv4. For example, Global Accelerator will not allow me to configure a dual-stack accelerator with an IPv4-only ALB endpoint. Also, for IPv6 ALB endpoints, client IP preservation must be enabled.
The UKUSA Agreement is an agreement between the United Kingdom, United States, Australia, Canada, and New Zealand to cooperatively collect, analyze, and share intelligence. Members of this group, known as the Five Eyes, focus on gathering and analyzing intelligence from different parts of the world. While Five Eyes countries have agreed to not spy on each other as adversaries, leaks by Snowden have revealed that some Five Eyes members monitor each other's citizens and share intelligence to avoid breaking domestic laws that prohibit them from spying on their own citizens. The Five Eyes alliance also cooperates with groups of third-party countries to share intelligence (forming the Nine Eyes and Fourteen Eyes); however, Five Eyes and third-party countries can and do spy on each other.
Typically, a TCP connection is established by using a three-way handshake (that is, three messages) between the client on the internet and the application endpoint in the AWS Region. So the farther away the client is from the endpoint, the longer the initial connection setup takes. With TCP termination at the edge, Global Accelerator reduces initial setup time by establishing a TCP connection between the client and the AWS edge location closest to the client. At nearly the same time, Global Accelerator creates a second TCP connection between the edge location and the application endpoint in the AWS Region. With this process, the client gets a faster response from the Global Accelerator edge location, and the connection from the edge location to the application endpoint in the Region is optimized to run over the AWS global network.
看起來 MySQL 系的 Global Database 就是跨區的 master-slave 架構 (所以標榜降低了 read latency，但沒有提到 write latency)：
An Amazon Aurora Global Database is a single database that spans multiple AWS regions, enabling low latency global reads and disaster recovery from region-wide outages.
另外可以看到是 1 秒，所以應該是 async replication：
Aurora Global Database replicates writes in the primary region with typical latency of <1 second to secondary regions, for low latency global reads.
然後可以跨區切換：
In disaster recovery situations, you can promote the secondary region to take full read-write responsibilities in under a minute.
看起來不是 multi-master (從 secondary region 這個字看)，所以寫入的部分還是得送回 primary region 處理：
Aurora Global Database uses storage-based replication with typical latency of less than 1 second, using dedicated infrastructure that leaves your database fully available to serve application workloads. In the unlikely event of a regional degradation or outage, one of the secondary regions can be promoted to full read/write capabilities in less than 1 minute.
AWS Global Accelerator is available in US East (N. Virginia), US East (Ohio), US West (Oregon), US West (N. California), Europe (Ireland), Europe (Frankfurt), Asia Pacific (Tokyo) and Asia Pacific (Singapore).
Global Tables – You can now create tables that are automatically replicated across two or more AWS Regions, with full support for multi-master writes, with a couple of clicks. This gives you the ability to build fast, massively scaled applications for a global user base without having to manage the replication process.
Updates are propagated to other Regions asynchronously via DynamoDB Streams and are typically complete within one second (you can track this using the new ReplicationLatency and PendingReplicationCount metrics).
不過如果是這樣的機制，conflict 的問題不知道怎麼解決... 文章裡面沒看到。
然後目前支援的區域還是有限：
Global Tables are available in the US East (Ohio), US East (N. Virginia), US West (Oregon), EU (Ireland), and EU (Frankfurt) Regions today, with more Regions in the works for 2018.
另外一個是備份與還原機制，有這樣的功能對很多計畫方便不少：
On-Demand Backup – You can now create full backups of your DynamoDB tables with a single click, and with zero impact on performance or availability. Your application remains online and runs at full speed. Backups are suitable for long-term retention and archival, and can help you to comply with regulatory requirements.
而備份還原機制是陸陸續續開放的，區域也有限：
We are rolling this new feature out on an account-by-account basis as quickly as possible, with initial availability in the US East (Northern Virginia), US East (Ohio), US West (Oregon), and EU (Ireland) Regions.
