I had the same alert. The capacity of the DN(datanode) was somehow assigned to the very small space. After reading the threads here, I was about to create a partition and mount it on a new DN directory. However, since I did not have any issue to use the /hadoop/hdfs/data which is in /(root) directory, I tried to find other way around and found that the amount of "Reserved space for HDFS" under the advanced tab was huge almost take whole unused space of the root directory. After downsize of "Reserved space for HDFS", every alert was solved. ... View more