linux上单机haoop配置笔记
先说一下我的环境
Win7
Visualbox4.2.10
ubuntu-12.04.2-desktop-i386.iso
hadoop0.20.2
jdk1.6.10

我的配置文件

Hosts

core-site.xml


mapred-site.xml




Masters

原因：
1.hadoop没有启动起来，可用jps看一下是否有相关的进程。
2.看一下core-site.xml中 的fs.default.nam的值是否为hdfs://localhost:9000


在hadoop安装目录下创建4个文件夹：
data1,data2,datalog1,datalog2


有时通过jps查看，发现找不到namenode进程，那么可以用bin/stop-all.sh关闭一下，然后格式化，之后再启动hadoop:




也可以直接运行hadoop自带的WordCount程序,其他步骤相同，只是不用自己打WordCount.jar，命令如下，这里有些奇怪，我反编译hadoop-0.20.2-examples.jar发现wordcount.class类的首字母为大写，但执行时非要用小写才行：
hadoop@hadoop-VirtualBox:~/wordcount$ hadoop  jar /usr/local/hadoop/hadoop-0.20.2-examples.jar wordcount input output413/03/28 14:59:41 INFO input.FileInputFormat: Total input paths to process : 213/03/28 14:59:41 INFO mapred.JobClient: Running job: job_201303281409_000913/03/28 14:59:42 INFO mapred.JobClient:  map 0% reduce 0%13/03/28 14:59:52 INFO mapred.JobClient:  map 100% reduce 0%13/03/28 15:00:04 INFO mapred.JobClient:  map 100% reduce 100%13/03/28 15:00:06 INFO mapred.JobClient: Job complete: job_201303281409_000913/03/28 15:00:06 INFO mapred.JobClient: Counters: 1713/03/28 15:00:06 INFO mapred.JobClient:   Job Counters 13/03/28 15:00:06 INFO mapred.JobClient:     Launched reduce tasks=113/03/28 15:00:06 INFO mapred.JobClient:     Launched map tasks=213/03/28 15:00:06 INFO mapred.JobClient:     Data-local map tasks=213/03/28 15:00:06 INFO mapred.JobClient:   FileSystemCounters13/03/28 15:00:06 INFO mapred.JobClient:     FILE_BYTES_READ=15213/03/28 15:00:06 INFO mapred.JobClient:     HDFS_BYTES_READ=6113/03/28 15:00:06 INFO mapred.JobClient:     FILE_BYTES_WRITTEN=37413/03/28 15:00:06 INFO mapred.JobClient:     HDFS_BYTES_WRITTEN=7313/03/28 15:00:06 INFO mapred.JobClient:   Map-Reduce Framework13/03/28 15:00:06 INFO mapred.JobClient:     Reduce input groups=1113/03/28 15:00:06 INFO mapred.JobClient:     Combine output records=1413/03/28 15:00:06 INFO mapred.JobClient:     Map input records=413/03/28 15:00:06 INFO mapred.JobClient:     Reduce shuffle bytes=8013/03/28 15:00:06 INFO mapred.JobClient:     Reduce output records=1113/03/28 15:00:06 INFO mapred.JobClient:     Spilled Records=2813/03/28 15:00:06 INFO mapred.JobClient:     Map output bytes=11813/03/28 15:00:06 INFO mapred.JobClient:     Combine input records=1413/03/28 15:00:06 INFO mapred.JobClient:     Map output records=1413/03/28 15:00:06 INFO mapred.JobClient:     Reduce input records=14hadoop@hadoop-VirtualBox:~/wordcount$ hadoop fs -ls output4Found 2 itemsdrwxr-xr-x   - hadoop supergroup          0 2013-03-28 14:59 /user/hadoop/output4/_logs-rw-r--r--   2 hadoop supergroup         73 2013-03-28 14:59 /user/hadoop/output4/part-r-00000