[HADOOP-692] Rack-aware Replica Placement - ASF JIRA

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Details

Type: Improvement
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: 0.10.1
Fix Version/s: 0.11.0
Component/s: None
Labels:
None

Description

This issue assumes that HDFS runs on a cluster of computers that spread across many racks. Communication between two nodes on different racks needs to go through switches. Bandwidth in/out of a rack may be less than the total bandwidth of machines in the rack. The purpose of rack-aware replica placement is to improve data reliability, availability, and network bandwidth utilization. The basic idea is that each data node determines to which rack it belongs at the startup time and notifies the name node of the rack id upon registration. The name node maintains a rackid-to-datanode map and tries to place replicas across racks.