Web页面出现一些错误：
namenode 出现 missing blocks的解决方案
There are 2 missing blocks. The following files may be corrupted:
blk_1078468526 /user/spark/sparkstreamingcheckpoint/checkpoint-1517487380000
blk_1078468528 /user/spark/sparkstreamingcheckpoint/checkpoint-1517487400000
Please check the logs or run fsck in order to identify the missing blocks. See the Hadoop FAQ for common causes and potential solutions.
通过 hdfs dfs -cat /user/spark/sparkstreamingcheckpoint/checkpoint-1517487380000 发现确实有两个blocks丢失
这两个blocks的两个副本都丢失了，所以才导致hdfs发出这个警告。
数据已经无法恢复，只能通过命令删除元数据来消除警告。
hdfs dfs -rm -r -f /user/spark/sparkstreamingcheckpoint/checkpoint-*
一旦出现这种情况，数据基本无法恢复，所以配置HDFS的副本数时尽可能3个以上。
来源：https://www.cnblogs.com/Vowzhou/p/10922066.html