First Run in RPi Cluster, HiBench Sort

gistfile1.txt

15/02/19 06:37:37 INFO mapreduce.Job:  map 100% reduce 96%
15/02/19 06:37:57 INFO mapreduce.Job:  map 100% reduce 97%
15/02/19 06:38:13 INFO mapreduce.Job:  map 100% reduce 98%
15/02/19 06:38:31 INFO mapreduce.Job:  map 100% reduce 99%
15/02/19 06:38:48 INFO mapreduce.Job:  map 100% reduce 100%
15/02/19 06:38:59 INFO mapreduce.Job: Job job_1424320958758_0001 completed successfully
15/02/19 06:39:00 INFO mapreduce.Job: Counters: 53
	File System Counters
		FILE: Number of bytes read=11131257
		FILE: Number of bytes written=181368960
		FILE: Number of read operations=0
		FILE: Number of large read operations=0
		FILE: Number of write operations=0
		HDFS: Number of bytes read=14893282
		HDFS: Number of bytes written=11736202
		HDFS: Number of read operations=4864
		HDFS: Number of large read operations=0
		HDFS: Number of write operations=512
	Job Counters 
		Failed map tasks=1
		Failed reduce tasks=3
		Launched map tasks=1025
		Launched reduce tasks=259
		Other local map tasks=1
		Data-local map tasks=743
		Rack-local map tasks=281
		Total time spent by all maps in occupied slots (ms)=32667758
		Total time spent by all reduces in occupied slots (ms)=49736756
		Total time spent by all map tasks (ms)=16333879
		Total time spent by all reduce tasks (ms)=12434189
		Total vcore-seconds taken by all map tasks=16333879
		Total vcore-seconds taken by all reduce tasks=12434189
		Total megabyte-seconds taken by all map tasks=4181473024
		Total megabyte-seconds taken by all reduce tasks=6366304768
	Map-Reduce Framework
		Map input records=61635
		Map output records=61635
		Map output bytes=40626306
		Map output materialized bytes=27883979
		Input split bytes=123904
		Combine input records=0
		Combine output records=0
		Reduce input groups=61635
		Reduce shuffle bytes=27883979
		Reduce input records=61635
		Reduce output records=61635
		Spilled Records=123270
		Shuffled Maps =262144
		Failed Shuffles=4
		Merged Map outputs=262144
		GC time elapsed (ms)=693827
		CPU time spent (ms)=4247680
		Physical memory (bytes) snapshot=185925271552
		Virtual memory (bytes) snapshot=489627824128
		Total committed heap usage (bytes)=125499088896
	Shuffle Errors
		BAD_ID=0
		CONNECTION=0
		IO_ERROR=4
		WRONG_LENGTH=0
		WRONG_MAP=0
		WRONG_REDUCE=0
	File Input Format Counters 
		Bytes Read=14769378
	File Output Format Counters 
		Bytes Written=11736202
Job ended: Thu Feb 19 06:39:00 UTC 2015
The job took 6956 seconds.
== MR job done==
15/02/19 06:39:06 INFO client.RMProxy: Connecting to ResourceManager at radoop0/192.168.0.2:8032