In order to use Hadoop 2.6 storage policies you must specify the type for each mount point in dfs.datanode.data.dir the type (DISK, ARCHIVE, RAM_DISK, SSD). If editing the hdfs-site.xml file directly I would do -   <property> <name>dfs.datanode.data.dir</name> <value>[ARCHIVE]file:///mnt/archive/dfs/dn,[SSD]file:///mnt/flash/dfs/dn,[DISK]file:///mnt/disk/dfs/dn</value> </property> However, if I try and use this format in the CM GUI I get the following error -  DataNode Data Directory: Path [ARCHIVE]:///mnt/archive/dfs/dn does not conform to the pattern "(/[-+=_.a-zA-Z0-9]+)+(/)*" DataNode Data Directory: Path [DISK]:file///mnt/disk/dfs/dn does not conform to the pattern "(/[-+=_.a-zA-Z0-9]+)+(/)*" DataNode Data Directory: Path [SSD]:file///mnt/flash/dfs/dn does not conform to the pattern "(/[-+=_.a-zA-Z0-9]+)+(/)*"   Does anyone know what is the correct format to specify storage tiers in the GUI or how to manually bypass the GUI and configure this.   Thank you    Daniel     ... View more