EC2 提供短期 RI 選項...

摘要： Amazon EC2 推出了短期 RI 選項：「Amazon EC2 now offers On-Demand Capacity Reservations 」。 最早的 RI 設計包括了「保證一定開的起來」與「折扣」，但後來AWS 大概是發現大家都是要「折扣...

ofollow,noindex" target="_blank">Amazon EC2 推出了短期 RI 選項：「Amazon EC2 now offers On-Demand Capacity Reservations 」。

最早的 RI 設計包括了「保證一定開的起來」與「折扣」，但後來AWS 大概是發現大家都是要「折扣」而不是保證開的起來，所以就開放了只有 discount 的部份。把原來有保證一定開的起來的部份變成 Zonal Reserved Instances。

不過 Zonal Reserved Instances 最少要一年 (有對應的折扣)，這次規劃的 On-Demand Capacity Reservations 可以隨時取消，但是就沒折扣了：

Previously in order to achieve a capacity reservation, customers had to leverage Zonal Reserved Instances and commit to that capacity for a minimum of one year. Now with On-Demand Capacity Reservations, customers can reserve the exact capacity they need, in the location they need, and can keep it only for as long as they need it.

不過費用計算上會組合已經買的 Regional RI，如果沒被用掉的話還是可以將對應的折扣拿進來用：

If you have Regional RI discounts, they will automatically apply to any matching Capacity Reservation. This gives you the flexibility to selectively add capacity reservations and still get the Regional RI discounts for that usage.

算是對需要「保證開的起來」的單位提供短期的彈性，實際上後面應該是去 spot instance 那邊踢一些機器出來？XD