? as of hadoop-2.5.1,there ?are some important features of hadoop 2.x for me to learn these days
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| new key features | abstract |
| NN HA (high availability) | standby meta node,failure over anytime,same as?
hbase-backup master |
| RM HA | same as above |
| HDFS Federation | union all nameapes from different rights |
| HDFS snapshot | ? |
| exeuction framework YARN | run any type apps what you want on it,eg. MR,DAG... |
| short circuit reads | speed up the reads |
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? of ?course,relate to hadoop 1.x,increasing learnings are important,as this will save you lot of time to study from scatch,you only need to focus the key features or new components what you want to see only!
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ref:
useful official docs about hadoop architecture
Hadoop 0.23.x/NameNode federation原理、编译、安装、体验
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原文：http://leibnitz.iteye.com/blog/2153744