#default attr values
/opt/rocks/bin/rocks add attr OSG_HadoopNameNode value="compute-0-0"
/opt/rocks/bin/rocks add attr OSG_HadoopDataDir value="/hadoop"
/opt/rocks/bin/rocks add attr OSG_HadoopData value="/hadoop/data"
/opt/rocks/bin/rocks add attr OSG_HadoopCheckPointDirs value="/home/hadoop,/scratch/hadoop"
/opt/rocks/bin/rocks add attr OSG_HadoopCheckPointPeriod value="600"
/opt/rocks/bin/rocks add attr OSG_HadoopUpdateFstab value="1"
/opt/rocks/bin/rocks add attr OSG_hdfsuid value=458
/opt/rocks/bin/rocks add attr OSG_hadoopgid value=409
/opt/rocks/bin/rocks add attr OSG_mapreduid value=461
/opt/rocks/bin/rocks add attr OSG_mapredgid value=461
#
these rocks attr set values for /etc/sysconfig/hadoop

    HADOOP_NAMENODE             --> &OSG_HadoopNameNode;         (compute-0-0) 
    HADOOP_REPLICATION_DEFAULT  --> not attr                         2
    HADOOP_DATADIR              --> &OSG_HadoopDataDir;          (/hadoop)
    HADOOP_DATA                 --> &OSG_HadoopData;             (/hadoop/data)
    HADOOP_GANGLIA_ADDRESS      --> &ganglia_address;            (224.0.0.3)
    HADOOP_SECONDARY_NAMENODE   --> &OSG_HadoopSecondaryNode;    (compute-0-1)
    HADOOP_CHECKPOINT_DIRS      --> &OSG_HadoopCheckPointDirs;   (/home/hadoop,/scratch/hadoop)
    HADOOP_CHECKPOINT_PERIOD    --> &OSG_HadoopCheckPointPeriod; (600)
    HADOOP_UPDATE_FSTAB         --> &OSG_HadoopUpdateFstab;      (1)

They can be changed with "rocks set attr"

in case of change uid/gid attr (like OSG_hadoopgid) also requires manually change in /etc/group on frontend since groups 
are exported to nodes. 
Warning: change of OSG_hdfsuid requires additional manually change in /etc/passwd and /export/home/hadoop on frontend to 
correct ownership (/usr/sbin/usermod -u newuid hdfs could be enough).