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https://issues.apache.org/jira/browse/HDFS-9624?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15088877#comment-15088877
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Kai Zheng commented on HDFS-9624:
---------------------------------
Thanks Yiqun for the update! Is it possible to refactor the test so the two
test methods can share most of the codes?
> DataNode start slowly due to the initial DU command operations
> --------------------------------------------------------------
>
> Key: HDFS-9624
> URL: https://issues.apache.org/jira/browse/HDFS-9624
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.7.1
> Reporter: Lin Yiqun
> Assignee: Lin Yiqun
> Attachments: HDFS-9624.001.patch, HDFS-9624.002.patch,
> HDFS-9624.003.patch
>
>
> It seems starting datanode so slowly when I am finishing migration of
> datanodes and restart them.I look the dn logs:
> {code}
> 2016-01-06 16:05:08,118 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Added
> new volume: DS-70097061-42f8-4c33-ac27-2a6ca21e60d4
> 2016-01-06 16:05:08,118 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Added
> volume - /home/data/data/hadoop/dfs/data/data12/current, StorageType: DISK
> 2016-01-06 16:05:08,176 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl:
> Registered FSDatasetState MBean
> 2016-01-06 16:05:08,177 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Adding
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544
> 2016-01-06 16:05:08,178 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data2/current...
> 2016-01-06 16:05:08,179 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data3/current...
> 2016-01-06 16:05:08,179 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data4/current...
> 2016-01-06 16:05:08,179 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data5/current...
> 2016-01-06 16:05:08,180 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data6/current...
> 2016-01-06 16:05:08,180 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data7/current...
> 2016-01-06 16:05:08,180 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data8/current...
> 2016-01-06 16:05:08,180 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data9/current...
> 2016-01-06 16:05:08,181 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data10/current...
> 2016-01-06 16:05:08,181 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data11/current...
> 2016-01-06 16:05:08,181 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Scanning
> block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on volume
> /home/data/data/hadoop/dfs/data/data12/current...
> 2016-01-06 16:09:49,646 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data7/current: 281466ms
> 2016-01-06 16:09:54,235 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data9/current: 286054ms
> 2016-01-06 16:09:57,859 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data2/current: 289680ms
> 2016-01-06 16:10:00,333 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data5/current: 292153ms
> 2016-01-06 16:10:05,696 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data8/current: 297516ms
> 2016-01-06 16:10:11,229 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data6/current: 303049ms
> 2016-01-06 16:10:28,075 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data12/current: 319894ms
> 2016-01-06 16:10:33,017 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data4/current: 324838ms
> 2016-01-06 16:10:40,177 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data10/current: 331996ms
> 2016-01-06 16:10:44,882 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data3/current: 336703ms
> 2016-01-06 16:11:14,241 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Time
> taken to scan block pool BP-1942012336-xx.xx.xx.xx-1406726500544 on
> /home/data/data/hadoop/dfs/data/data11/current: 366060ms
> 2016-01-06 16:11:14,242 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Total
> time to scan all replicas for block pool
> BP-1942012336-xx.xx.xx.xx-1406726500544: 366065ms
> {code}
> And I know that Scanning blocks on volume and then calculating the dfsUsed
> costs the most of time. Because my datanode's migiration costs the much time,
> so that dfsUsed value can't use cache-dfsused and should be doing du
> operations. But actually I don't need do it again because there has no
> operations in these datanodes. The info is these:
> {code}
> /**
> * Read in the cached DU value and return it if it is less than 600 seconds
> * old (DU update interval). Slight imprecision of dfsUsed is not critical
> and
> * skipping DU can significantly shorten the startup time. If the cached
> value
> * is not available or too old, -1 is returned.
> * */
> {code}
> The 600 seconds is a dead code. And it looks not suitable for here.
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