AWS Glacier是去年8月份推出的备份服务,价格低廉,大体上每个GB每月1美分,这个价格比S3或者其他存储低一个数量级。但是这个系统的读能力相当低,用户发出查询请求后,可能需要3-5个小时才能将数据读出来,用户程序可以通过SNS服务获得通知。具体能力如下:
- Native 256-bit AES encryption
- 99.999999999% annual data durability guarantee per object
- AWS Import/Export support for bulk data migration
- Multi-part uploading
- (coming soon) a system for automatically migrating data between S3 and Glacier with lifecycle policies
有些媒体猜测其后端采用了带库,因此响应时间很长,但其实并非如此,有多个地方提到了可能的后端系统:
(1)Sintaks是AWS的前雇员,应该是存储产品线的。给出的结论比较靠谱,即价格低廉的原因是由于定制化硬件,据说采用了低转速的省电磁盘,并且提供了可编程的关闭电源的能力。主板和机架也都是定制化的,尤其是主板设计,采用了非常低功耗的设计。具体条带化设计策略不详,如果采用S3所采用的纠删码,则分片写是串行的。这个系统将节省S3用户的成本。
(2)Christopher Petrilli是个geek,计算了AWS的硬件设备成本。大体如下:估计采用了3TB的SATA磁盘(单价75$左右),考虑到副本、纠删码等冗余设计,按照三倍计算,每GB成本是0.075美元。参考BackBlaze的价格,估计每个GB是0.1美元,因此估计1年以后AWS才能通过Glacier挣钱,估计是7-10年可用。此处没有计入太多能耗因素,因为可以关闭磁盘。结合Sintaks的信息,由于实际定制化磁盘,因此价格会更低,AWS盈利时间会大大缩短。
(3)JRH:Tape has long been the media of choice for very cold workloads and tape remains an excellent choice at scale. What’s unfortunate, is that the scale point where tape starts to win has been going up over the years. High-scale tape robots are incredibly large and expensive. The good news is that very high-scale storage customers like Large Hadron Collider (LHC) are very well served by tape. But, over the years, the volume economics of tape have been moving up scale and fewer and fewer customers are cost effectively served by tape
小结一下,Glacier:
(1)硬件采用了定制化节能硬件,并且写满后就关闭磁盘
(2)软件可能基于S3的定制化
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AWS 官方的介绍材料,并没有透露任何有价值的信息
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相关信息:
- AWS Glacier’s dazzling price benefits melt next to the cost of tape
- Amazon Glacier: 99.999999999% durability long-term storage, for a penny a gig
- JRH:Glacier: Engineering for Cold Data Storage in the Cloud
- http://news.ycombinator.com/item?id=4411536
- http://www.quora.com/Amazon-Glacier/Which-existing-AWS-systems-back-Amazon-Glacier
- http://www.slideshare.net/AmazonWebServices/session-3jp
- http://www.slideshare.net/AmazonWebServices/aws-services-overview-ryland