Vinayakumar B created HDFS-6114:
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             Summary: Block Scan log rolling will never happen if blocks 
written continuously leading to huge size of dncp_block_verification.log.curr
                 Key: HDFS-6114
                 URL: https://issues.apache.org/jira/browse/HDFS-6114
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: datanode
    Affects Versions: 2.3.0
            Reporter: Vinayakumar B
            Assignee: Vinayakumar B
            Priority: Critical


1. {{BlockPoolSliceScanner#scan()}} will not return until all the blocks are 
scanned. 
2. If the blocks (with size in several MBs) to datanode are written 
continuously 
then one iteration of {{BlockPoolSliceScanner#scan()}} will be continously 
scanning the blocks
3. These blocks will be deleted after some time (enough to get block scanned)
4. As Block Scanning is throttled, So verification of all blocks will take so 
much time.
5. Rolling will never happen, so even though the total number of blocks in 
datanode doesn't increases, entries ( which contains stale entries of deleted 
blocks) in *dncp_block_verification.log.curr* continuously increases leading to 
huge size.

In one of our env, it grown more than 1TB where total number of blocks were 
only ~45k.






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