Tag: hdd

Amazon EBS 推出了新的磁碟種類，都是比現在更經濟 (白話文：更便宜) 的方案：「Amazon EBS Update – New Cold Storage and Throughput Options」。

第一種是 Amazon EBS Throughput Optimized HDD，代號是 st1；第二種是 Amazon EBS Cold HDD，代號是 sc1，兩種都是傳統磁頭硬碟。

第一種 st1 重視 sequential 的 throughput：

Starts at 250 MB/s for a 1 terabyte volume, and grows by 250 MB/s for every additional provisioned terabyte until reaching a maximum burst throughput of 500 MB/s.

第二種 sc1 則是重視堆資料的費用：

Designed for workloads similar to those for Throughput Optimized HDD that are accessed less frequently; $0.025 / gigabyte / month.

要注意的是，IOPS 是可以累計的，而未滿 1MB 的 access 會計算成 1MB，所以只適合大量 sequential access 的應用，像是 Hadoop 這類 big data 類的應用：

For both of the new magnetic volume types, the burst credit bucket can grow until it reaches the size of the volume. In other words, when a volume’s bucket is full, you can scan the entire volume at the burst rate. Each I/O request of 1 megabyte or less counts as 1 megabyte’s worth of credit. Sequential I/O operations are merged into larger ones where possible; this can increase throughput and maximizes the value of the burst credit bucket (to learn more about how the bucket operates, visit the Performance Burst Details section of my New SSD-Backed Elastic Block Storage post).

另外 sc1 也是目前每單位裡面最便宜的價錢，不知道拿來當 root 會底多慢 XDDD