Hi, Recently, I'm playing with the network topology script and the scenario that datanode comes back from dead with rack location changed. I did few experiments:
1) just stop datanode 2) just stop datanode, remove data storage dir 3) decommission node 4) decommission node, remove data storage dir The time from death to life is about one week. However, it seems that somehow the namenode uses the old rack localtion for those nodes. I have to restart the namenode in order to get the rack information correctly. However, I roughly checked the source, it seems to me that under some circumstances the namenode will re-query the topology script. Would someone please explain this in more details? (the HDFS docs on hadoop site is not very clear about the network topology part) Thanks, Rong-En Fan
