Q:

Why doesnt Hadoop work with Windows 7 under cygwin?

I am trying to install and start hadoop 1.1.2 in cygwin on windows 7. I am getting the following issue when attempting to run a simple job:
bin/hadoop jar hadoop-*-examples.jar pi 10 100

13/04/26 17:56:10 WARN hdfs.DFSClient: DataStreamer Exception: org.apache.hadoop.ipc.RemoteException: java.io.IOException: File /user/username/PiEstimator_TMP_3_141592654/in/part0 could only be replicated to 0 nodes, instead of 1
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1639)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:736)
        at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)

My configuration is as follows:
mapred-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>
<property>
<name>mapred.job.tracker</name>
<value>localhost:9001</value>
</property>
</configuration>

hdfs-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>
<property>
<name>dfs.replication</name>
<value>1</value>
</property>
</configuration>

core-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://localhost:9000</value>
</property>
</configuration>

A:

The answer is in the logs.  There will be a specific exception detailed there, most likely a file access problem requiring you to chmod 755 -R some directory and its contents.

