Amazon DynamoDB Accelerator (DAX)

DynamoDB 推出的新架構,在系統上幫忙處理 cache:「Amazon DynamoDB Accelerator (DAX) – In-Memory Caching for Read-Intensive Workloads」。

DAX 跟現有的 DynamoDB API 相容:

DAX is a fully managed caching service that sits (logically) in front of your DynamoDB tables. It operates in write-through mode, and is API-compatible with DynamoDB.

因為 cache 的緣故,會是 eventually-consistent 架構:

Responses are returned from the cache in microseconds, making DAX a great fit for eventually-consistent read-intensive workloads.

然後是 r3 系列的機器組成的,限制在十台 (冒出大大的問號):

Each DAX cluster can contain 1 to 10 nodes; you can add nodes in order to increase overall read throughput. The cache size (also known as the working set) is based on the node size (dax.r3.large to dax.r3.8xlarge) that you choose when you create the cluster. Clusters run within a VPC, with nodes spread across Availability Zones.

不是很清楚這樣的好處 (比起自己用 memcached 或是其他類似的 cache 架構),也許過幾天想通了會開竅... :o

Amazon EC2 的 C4、M4、R3 降價 (約 5%)

應該是各項成本的降低的順勢降價,幅度約 5%:「Happy New Year – EC2 Price Reduction (C4, M4, and R3 Instances)」。

C4 與 R3 是針對 CPU 與記憶體,M4 則是一般性的 instance,都是最新的系列。看起來是累積到過年後發一篇用的?價錢馬上生效,同時 On-Demand 的部份回朔到月初:

Changes to the On-Demand and Dedicated host pricing are retroactive to the beginning of the month (January 1, 2016); the new Reserved instance pricing is in effect today. During the month, your billing estimates may not reflect the reduced prices. They will be reflected in the statement at the end of the month.


EC2 instance Auto Recovery 功能全區開放

Twitter 上看到公告:「Announcement: EC2 instance Auto Recovery now available in 8 more AWS Regions」。

也就是 C3、C4、M3、R3、T2 這五種 instance 都可以開 Auto Recovery,而且必須在 VPC 內的 EBS-only instance。

在某種程度上的 High Availability 機制可以直接用這個功能解決掉。