昨天 Amazon EC2 的 Reserved Instance 有了重大的變化：「EC2 Reserved Instance Update – Convertible RIs and Regional Benefit」。
當初 AWS 規劃 RI 的重點在於「保留」而不是「折扣」，所以在整體的規劃上你可以看到都是以「保留」為想法在規劃 (像是購買時要到 region + zone 的層級)。但其實更多人是看中他的「折扣」，所以 AWS 這次乾脆推出了不分區的「折扣」方案 (購買時只指定 region)，當然使用者就要規劃成 a 區開不起來就去開 b 區的機器：
Many customers have told us that the discount is more important than the capacity reservation, and that they would be willing to trade it for increased flexibility. Starting today, you can choose to waive the capacity reservation associated with Standard RI, run your instance in any AZ in the Region, and have your RI discount automatically applied.
另外是 RI 之間的轉換，現在可以透過系統直接轉不同 type 的 RI 了：
Convertible RIs give you even more flexibility and offer a significant discount (typically 45% compared to On-Demand). They allow you to change the instance family and other parameters associated with a Reserved Instance at any time. For example, you can convert C3 RIs to C4 RIs to take advantage of a newer instance type, or convert C4 RIs to M4 RIs if your application turns out to need more memory.
不過相較於隔壁的 Google Cloud Engine 的 discount 是完全自動算 (不需要先買 RI 這類的產品) 還是差了不少...