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"Configured Capacity" shows less size than the original disk capacity as per dfsadmin command

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"Configured Capacity" shows less size than the original disk capacity as per dfsadmin command

I have implemented 2 node cluster using Cloudera Manager 5.4.1 in VMWare workstation and this includes components like Hbase, Impala, Hive, Sqoop2, Oozie, Zookeeper, NameNode, SecondaryName and YARN.

I have simulated 3 disk drives per node which includes sda for OS , sdb & sdc for Hadoop storage.

 

 As I had allocated sdb1 having 16GB and sdc1 having 16GB  dedicated for Hadoop storage on each of the nodes. Hence I assume that my total capacity for HDFS storage including both nodes should be 64GB. But when checked the output using dfsadmin command and also using NameNode UI, I see that the "Configured Capacity is lesser than my original disk size allocated for HDFS".

I have shown the output of dfsadmin command below and also output of df -h is shown. Kindly help me understand why the Configured capacity is showing lesser than my original disk size ?

 

[hduser@node1 ~]$ df -h
Filesystem                     Size  Used Avail Use% Mounted on
/dev/mapper/vg_node1-LogVol00   40G   15G   23G  39% /
tmpfs                          3.9G   76K  3.9G   1% /dev/shm
/dev/sda1                      388M   39M  329M  11% /boot
/dev/sdb1                       16G  283M   15G   2% /disks/disk1/hdfsstorage/dfs
/dev/sdc1                       16G  428M   15G   3% /disks/disk2/hdfsstorage/dfs
/dev/sdb2                      8.1G  147M  7.9G   2% /disks/disk1/nonhdfsstorage
/dev/sdc2                      8.1G  147M  7.9G   2% /disks/disk2/nonhdfsstorage
cm_processes                   3.9G  5.8M  3.9G   1% /var/run/cloudera-scm-agent/process
[hduser@node1 ~]$

 

[hduser@node1 zookeeper]$ sudo -u hdfs hdfs dfsadmin -report
[sudo] password for hduser:
Configured Capacity: 47518140008 (44.25 GB)
Present Capacity: 47518140008 (44.25 GB)
DFS Remaining: 46728742571 (43.52 GB)
DFS Used: 789397437 (752.83 MB)
DFS Used%: 1.66%
Under replicated blocks: 385
Blocks with corrupt replicas: 0
Missing blocks: 0
Missing blocks (with replication factor 1): 0

-------------------------------------------------
Live datanodes (2):

Name: 192.168.52.111:50010 (node1.example.com)
Hostname: node1.example.com
Rack: /default
Decommission Status : Normal
Configured Capacity: 23759070004 (22.13 GB)
DFS Used: 394702781 (376.42 MB)
Non DFS Used: 0 (0 B)
DFS Remaining: 23364367223 (21.76 GB)
DFS Used%: 1.66%
DFS Remaining%: 98.34%
Configured Cache Capacity: 121634816 (116 MB)
Cache Used: 0 (0 B)
Cache Remaining: 121634816 (116 MB)
Cache Used%: 0.00%
Cache Remaining%: 100.00%
Xceivers: 2
Last contact: Sun May 15 18:15:33 IST 2016


Name: 192.168.52.112:50010 (node2.example.com)
Hostname: node2.example.com
Rack: /default
Decommission Status : Normal
Configured Capacity: 23759070004 (22.13 GB)
DFS Used: 394694656 (376.41 MB)
Non DFS Used: 0 (0 B)
DFS Remaining: 23364375348 (21.76 GB)
DFS Used%: 1.66%
DFS Remaining%: 98.34%
Configured Cache Capacity: 523239424 (499 MB)
Cache Used: 0 (0 B)
Cache Remaining: 523239424 (499 MB)
Cache Used%: 0.00%
Cache Remaining%: 100.00%
Xceivers: 2
Last contact: Sun May 15 18:15:32 IST 2016

 

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Re: "Configured Capacity" shows less size than the original disk capacity as per dfsadmin

Explorer
4 REPLIES 4

Re: "Configured Capacity" shows less size than the original disk capacity as per dfsadmin

Explorer

As per your df -h output, the sdb2 and sdc2 has size of 8GB each not 16G:

 

/dev/sdb2                      8.1G  147M  7.9G   2% /disks/disk1/nonhdfsstorage
/dev/sdc2                      8.1G  147M  7.9G   2% /disks/disk2/nonhdfsstorage

 

 

Re: "Configured Capacity" shows less size than the original disk capacity as per dfsadmin

Hi Vina,

 

As you can see from the output, sdb2 and sdc2 are allocated for nonhdfsstorgae (ex: intermediate data). sdb1 and sdc1 are the partition drives which are mounted for hdfs storage and they are of 16GB each as you can see in "df -h" output.

[hduser@node1 ~]$ df -h
Filesystem                     Size  Used Avail Use% Mounted on
/dev/sdb1                       16G  283M   15G   2% /disks/disk1/hdfsstorage/dfs
/dev/sdc1                       16G  428M   15G   3% /disks/disk2/hdfsstorage/dfs

Can you please help.

Re: "Configured Capacity" shows less size than the original disk capacity as per dfsadmin

Explorer

Re: "Configured Capacity" shows less size than the original disk capacity as per dfsadmin

Yes the link was helpful. 
As per the property "dfs.datanode.du.reserved", it was configured to use 4.25 GB and hence I consider now that 4.25 GB is allocated for each data directory in a given node. Since I had two data directory partitions, the reserved space combined would be 8.5 GB per node and which brings the configured capacity on each node to be 23.5 GB (32GB - 8.5GB).
I arrived at the following formula === >

Configured Capacity = Total Disk Space allocated for Data Directories (dfs.data.dir) - Reserved Space for Non DFS Use (dfs.datanode.du.reserved)