This comes quite handy, e.g., when you need to setup firewall rules.
On my Windows 8 machine, I had to add the following lines to the hdfs-site.xml that comes with hortonworks hdp 1 distribution
<property> <name>dfs.datanode.data.dir.perm</name> <value>700</value> <description>The permissions that should be there on dfs.data.dir directories. The datanode will not come up if the permissions are different on existing dfs.data.dir directories. If the directories don't exist, they will be created with this permission. </description> </property>