https://www.bigdataschool.ru/blog/hadoop-%d0%b4%d0%b8%d1%81%d1%82%d1%80%d0%b8%d0%b1%d1%83%d1%82%d0%b8%d0%b2-%d1%81%d1%80%d0%b0%d0%b2%d0%bd%d0%b5%d0%bd%d0%b8%d0%b5.html