這次 re:Invent 關於 Amazon EFS 推出來的新東西，目前有看到兩個，第一個是「New – Announcing Amazon EFS Elastic Throughput」，介紹 Elastic Throughput。
傳統的 Busrting Throughput 模式會依照你的使用空間分配對應的速度，基礎是 50MB/sec per TB 計算，但可以 burst 到 100MB/sec per TB：
When burst credits are available, a file system can drive throughput up to 100 MiBps per TiB of storage, up to the Amazon EFS Region's limit, with a minimum of 100 MiBps. If no burst credits are available, a file system can drive up to 50 MiBps per TiB of storage, with a minimum of 1 MiBps.
而 Elastic Throughput 是一種高效能的模式，可以提供 3GB/sec 的讀取速度與 1GB/sec 的寫入速度：
Elastic Throughput allows you to drive throughput up to a limit of 3 GiB/s for read operations and 1 GiB/s for write operations per file system in all Regions.
但這然是有代價的，Elastic Throughput 的計費方式按照傳輸量計算，以 us-east-1 的計價來說，讀取是 $0.03/GB，寫入是 $0.06/GB。
粗粗算了一下，比較適合短時間要很大量快速讀寫的應用。如果是不在意時間的 (像是 cron job) 就不需要 Elastic Throughput... 然後 home 目錄拿來用可能是個不錯的選擇？
第二個推出的項目是不用錢的，是 Amazon EFS 效能的改進，降低 latency：「AWS announces lower latencies for Amazon Elastic File System」。
首先是讀取的效能提昇，以敘述看起來像是加上了 cache 層產生的效能改進：
Amazon EFS now delivers up to 60% lower read operation latencies when working with frequently-accessed data and metadata.
另外是對小檔寫入有做處理：
In addition, EFS now delivers up to 40% lower write operation latencies when working with small files (<64 KB) and metadata.
不過這些改進只有在新的 EFS 才會有，而且這波只有 us-east-1 上：
These enhancements are available automatically for all new EFS file systems using General Purpose mode in the US East (N. Virginia) Region, and will become available in the remaining AWS commercial regions over the coming weeks.
