under replicated blocks 
Solution: Find the blocks that are not copied
Find the blocks that are not replicated.
hdfs fsck/| grep 'Under replicated' | awk -F':' '{print 1}' >> /tmp/under_replicated_files 
Then loop to repair.
for hdfsfile in `cat /tmp/under_replicated_files`; do echo "Fixing $hdfsfile :" ; hadoop fs -setrep 3 $hdfsfile; done
output:
Fixing /user/hdfs/.staging/job_1547173493660_0405/job.jar :
Replication 3 set: /user/hdfs/.staging/job_1547173493660_0405/job.jar
Fixing /user/hdfs/.staging/job_1547173493660_0405/job.split :
Replication 3 set: /user/hdfs/.staging/job_1547173493660_0405/job.split
Fixing /user/hdfs/.staging/job_1547173493660_0481/job.jar :
Replication 3 set: /user/hdfs/.staging/job_1547173493660_0481/job.jar
Fixing /user/hdfs/.staging/job_1547173493660_0481/job.split :
Replication 3 set: /user/hdfs/.staging/job_1547173493660_0481/job.split
Fixing /user/hdfs/.staging/job_1547173493660_0483/job.jar :
Replication 3 set: /user/hdfs/.staging/job_1547173493660_0483/job.jar
Fixing /user/hdfs/.staging/job_1547173493660_0483/job.split :
Replication 3 set: /user/hdfs/.staging/job_1547173493660_0483/job.split
Fixing /user/hdfs/.staging/job_1547197402450_0021/job.jar :
Replication 3 set: /user/hdfs/.staging/job_1547197402450_0021/job.jar
Fixing /user/hdfs/.staging/job_1547197402450_0021/job.split :
Replication 3 set: /user/hdfs/.staging/job_1547197402450_0021/job.split