prefetch已经不再支持Aspera了

在之前的写的教程中，我讲到从NCBI下载SRA数据时，都会教大家配置Aspera，提高下载速度。

之前一直有人问我为什么最近无法prefetch下载数据时即便指定了ascp，但是依旧用HTTPS呢？我之前一直以为是该数据并不支持ascp的下载方式，结果现在发现是所有NCBI的SRA数据都不在支持了。

有人在Github上提问为什么 prefetch不能使用fasp下载，作者的回复内容如下

NCBI has shifted to using cloud-style object stores. The Aspera algorithm requires random disk access to perform its function, and random access to object stores gives very poor performance. If Aspera comes out with a server that works well on cloud and object stores, we will support it, but currently there is no Aspera support available to my knowledge.
prefetch is not canceling ascp support, as you say, but will remove the option from the command line in the next release because there will not be an Aspera server available for AWS, GCP or NCBI, making the option useless and misleading. It will be added back in if the situation changes.
见 https://github.com/ncbi/sra-tools/issues/255#issuecomment-566068771

也就是说NCBI改变了数据存放形式，导致原本ascp的下载方式效率低下，于是干脆就放弃了。

怎么说呢，真的坑啊！