CDH installation: Failed to create HDFS directory /tmp

[#1]

Hi, I am installing CDH with CM (Path C) , but I can't create HDFS directory /tmp successfully. The log shows:

2017-05-03 22:17:27,838 WARN org.apache.hadoop.hdfs.server.namenode.NameNodeResourceChecker: Space available on volume '/dev/disk/by-uuid/526841aa-13c2-4953-94ee-992b7f2fe6c9' is 0, which is below the configured reserved amount 104857600

2017-05-03 22:17:27,838 WARN org.apache.hadoop.hdfs.server.namenode.FSNamesystem: NameNode low on available disk space. Already in safe mode.

2017-05-03 22:17:27,838 INFO org.apache.hadoop.hdfs.StateChange: STATE* Safe mode is ONResources are low on NN. Please add or free up more resources then turn off safe mode manually. NOTE: If you turn off safe mode before adding resources, the NN will immediately return to safe mode. Use "hdfs dfsadmin -safemode leave" to turn safe mode off.

+ /opt/cloudera/parcels/CDH-5.4.7-1.cdh5.4.7.p0.3/lib/hadoop-hdfs/bin/hdfs --config /opt/cloudera-manager/cm-5.4.7/run/cloudera-scm-agent/process/60-hdfs-NAMENODE-createtmp dfs -mkdir -p /tmp mkdir: Cannot create directory /tmp. Name node is in safe mode.

+ '[' 1 -eq 0 ']' + echo 'Unable to create directory /tmp; see stderr log.'

+ exit 1

but when I check with 'df -h' , it shows I should have enough disk space:

lrwxrwxrwx 1 root root 10 Apr 22 09:35 /dev/disk/by-uuid/526841aa-13c2-4953-94ee-992b7f2fe6c9 -> ../../sda1

Filesystem Size Used Avail Use% Mounted on

udev 32G 4.0K 32G 1% /dev

tmpfs 6.3G 1.6M 6.3G 1% /run

/dev/sda1 212G 124G 78G 62% /

......

BTW, I have re-installed several times.

Any suggestion will be appreciated.

[#2]

1 . The root cause is  Namenode's disk is runining out of space . 

The log says it all 

2 . Since it is runining out of space , it is in safe mode . 

During Safemode  NameNode will be in  a read-only mode for the HDFS cluster,  it does not allow any modifications to file system or blocks.

Could you check the parameter in hdfs-site.xml 

dfs.namenode.resource.du.reserved 

 The default is 100 MB  - 104857600 - which what i am seeing the logs.

Please change  the above parameter accordinly and restart the namenode.

[#3]

I checked the disk space and it shows I do have enough space.