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Table 1 Hadoop’s basic configuration parameters

From: A Pareto-based scheduler for exploring cost-performance trade-offs for MapReduce workloads

Parameter Description Default
Mapred.reduce.tasks Number of reduce tasks 1
Io.sort.mb Map buffer size in MB 100
Io.sort.record.percent The percentage of the map buffer’s  
  size used for metadata 0.05
Io.sort.spill.percent Threshold in the map buffer’s size  
  that if exceeded in-memory data  
  are stored in local files 0.80
Dfs.block.size HDFS block size, determines the  
  number of map tasks 128 m