How to check if Hadoop daemons are running?

In the shell type 'jps' (you might need a jdk to run jps). It lists all the running java processes and will list out the hadoop daemons that are running.

If you see hadoop process is not running on ps -ef|grep hadoop, run sbin/start-dfs.sh. Monitor with hdfs dfsadmin -report:

[mapr@node1 bin]$ hadoop dfsadmin -report
Configured Capacity: 105689374720 (98.43 GB)
Present Capacity: 96537456640 (89.91 GB)
DFS Remaining: 96448180224 (89.82 GB)
DFS Used: 89276416 (85.14 MB)
DFS Used%: 0.09%
Under replicated blocks: 0
Blocks with corrupt replicas: 0
Missing blocks: 0

-------------------------------------------------
Datanodes available: 2 (2 total, 0 dead)

Name: 192.168.1.16:50010
Decommission Status : Normal
Configured Capacity: 52844687360 (49.22 GB)
DFS Used: 44638208 (42.57 MB)
Non DFS Used: 4986138624 (4.64 GB)
DFS Remaining: 47813910528(44.53 GB)
DFS Used%: 0.08%
DFS Remaining%: 90.48%
Last contact: Tue Aug 20 13:23:32 EDT 2013


Name: 192.168.1.17:50010
Decommission Status : Normal
Configured Capacity: 52844687360 (49.22 GB)
DFS Used: 44638208 (42.57 MB)
Non DFS Used: 4165779456 (3.88 GB)
DFS Remaining: 48634269696(45.29 GB)
DFS Used%: 0.08%
DFS Remaining%: 92.03%
Last contact: Tue Aug 20 13:23:34 EDT 2013