主题：【文摘】youtube architecture -- 西电鲁丁

好文章不敢独享，贴出来供大家参考。

http://highscalability.com/youtube-architecture

文章介绍了youtube网站的软件平台和主要的技术架构，重点是如何实现存储海量的视频和服务每日超过1亿的视频访问的。

摘要：

1. YouTube的软件平台全是开源的

# Apache

# Python

# Linux (SuSe)

# MySQL

# psyco, a dynamic python->C compiler

# lighttpd for video instead of Apache

2. Most popular content is moved to a CDN (content delivery network):

- CDNs replicate content in multiple places. There's a better chance of content being closer to the user, with fewer hops, and content will run over a more friendly network.

- CDN machines mostly serve out of memory because the content is so popular there's little thrashing of content into and out of memory.

# Less popular content (1-20 views per day) uses YouTube servers in various colo sites.

－Caching doesn't do a lot of good in this scenario, so spending money on more cache may not make sense. This is a very interesting point

3. Thumbnails （4 thumbnails for each video so there are a lot more thumbnails than videos）最初存放于LINUX EXT3的文件系统，已经到了目录下文件数的上限，决定采用Google's BigTable（记得河里的邓兄介绍过，不记得坑填完了没有）

4. MYSQL数据库存储META DATA(元数据），包括TAGS,描述等 。（其实大部分的ECM-企业内容管理系统也是采用数据库管理元数据，文件系统或数据库存储内容） Can now scale database almost arbitrarily.

令人惊讶的是YouTube的技术队伍只有9人，

2 sysadmins, 2 scalability software architects

2 feature developers, 2 network engineers, 1 DBA

这个应该会令很多网站汗颜。