Hadoop CDh4 Standby HA 启动过程

根据日志:
StandBy NN启动过程
1.获得Active NN Checkpoints信息
2.在内存中，注册Live Nodes
3.SB NN 进入Safe Mode
4.从Datanod获取包信息
5.离开Safe Mode

Checkpointing active NN at bigdata-4:50070
Serving checkpoints at bigdata-3/172.16.206.206:50070
2012-08-02 11:07:24,761 INFO org.apache.hadoop.hdfs.StateChange: BLOCK* NameSystem.registerDatanode: node registration from DatanodeRegistration(172.16.206.209, storageID=DS-1124007630-172.16.206.209-50010-1343796008920, infoPort=50075, ipcPort=50020, storageInfo=lv=-40;cid=CID-d1f20578-a690-4538-a945-c166fd41cda4;nsid=1959114293;c=0) storage DS-1124007630-172.16.206.209-50010-1343796008920
2012-08-02 11:07:24,763 INFO org.apache.hadoop.net.NetworkTopology: Adding a new node: /default-rack/172.16.206.209:50010
2012-08-02 11:07:24,763 INFO org.apache.hadoop.hdfs.StateChange: BLOCK* NameSystem.registerDatanode: node registration from DatanodeRegistration(172.16.206.206, storageID=DS-1236477555-172.16.206.206-50010-1343796211132, infoPort=50075, ipcPort=50020, storageInfo=lv=-40;cid=CID-d1f20578-a690-4538-a945-c166fd41cda4;nsid=1959114293;c=0) storage DS-1236477555-172.16.206.206-50010-1343796211132
2012-08-02 11:07:24,764 INFO org.apache.hadoop.net.NetworkTopology: Adding a new node: /default-rack/172.16.206.206:50010
2012-08-02 11:07:24,995 INFO org.apache.hadoop.hdfs.StateChange: STATE* Safe mode extension entered.
The reported blocks 8854 has reached the threshold 0.9990 of total blocks 8863. Safe mode will be turned off automatically in 29 seconds.
2012-08-02 11:07:24,995 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager: BLOCK* processReport: Received first block report from 172.16.206.209:50010 after becoming active. Its block contents are no longer considered stale.
2012-08-02 11:07:24,996 INFO org.apache.hadoop.hdfs.StateChange: BLOCK* processReport: from DatanodeRegistration(172.16.206.209, storageID=DS-1124007630-172.16.206.209-50010-1343796008920, infoPort=50075, ipcPort=50020, storageInfo=lv=-40;cid=CID-d1f20578-a690-4538-a945-c166fd41cda4;nsid=1959114293;c=0), blocks: 12908, processing time: 84 msecs
2012-08-02 11:07:25,041 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager: BLOCK* processReport: Received first block report from 172.16.206.206:50010 after becoming active. Its block contents are no longer considered stale.
2012-08-02 11:07:25,041 INFO org.apache.hadoop.hdfs.StateChange: BLOCK* processReport: from DatanodeRegistration(172.16.206.206, storageID=DS-1236477555-172.16.206.206-50010-1343796211132, infoPort=50075, ipcPort=50020, storageInfo=lv=-40;cid=CID-d1f20578-a690-4538-a945-c166fd41cda4;nsid=1959114293;c=0), blocks: 12908, processing time: 45 msecs
2012-08-02 11:07:44,998 INFO org.apache.hadoop.hdfs.StateChange: STATE* Safe mode ON.
The reported blocks 8863 has reached the threshold 0.9990 of total blocks 8863. Safe mode will be turned off automatically in 9 seconds.
2012-08-02 11:07:54,999 INFO org.apache.hadoop.hdfs.StateChange: STATE* Leaving safe mode after 32 secs.
2012-08-02 11:07:54,999 INFO org.apache.hadoop.hdfs.StateChange: STATE* Safe mode is OFF.
2012-08-02 11:07:54,999 INFO org.apache.hadoop.hdfs.StateChange: STATE* Network topology has 1 racks and 2 datanodes
2012-08-02 11:07:54,999 INFO org.apache.hadoop.hdfs.StateChange: STATE* UnderReplicatedBlocks has 0 blocks