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From "Hari Sekhon (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-8299) HDFS reporting missing blocks when they are actually present due to read-only filesystem
Date Thu, 30 Apr 2015 13:33:06 GMT

     [ https://issues.apache.org/jira/browse/HDFS-8299?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Hari Sekhon updated HDFS-8299:
    Attachment: datanode.log

> HDFS reporting missing blocks when they are actually present due to read-only filesystem
> ----------------------------------------------------------------------------------------
>                 Key: HDFS-8299
>                 URL: https://issues.apache.org/jira/browse/HDFS-8299
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode
>    Affects Versions: 2.6.0
>         Environment: Fsck shows missing blocks when the blocks can be found on a datanode's
filesystem and the datanode has been restarted to try to get it to recognize that the blocks
are indeed present and hence report them to the NameNode in a block report.
> Fsck output showing an example "missing" block:
> {code}/apps/hive/warehouse/<custom_scrubbed>.db/someTable/000000_0: CORRUPT blockpool
BP-120244285-<ip>-1417023863606 block blk_1075202330
>  MISSING 1 blocks of total size 3260848 B
> 0. BP-120244285-<ip>-1417023863606:blk_1075202330_1484191 len=3260848 MISSING!{code}
> The block is definitely present on more than one datanode however, here is the output
from one of them that I restarted to try to get it to report the block to the NameNode:
> {code}# ll /archive1/dn/current/BP-120244285-<ip>-1417023863606/current/finalized/subdir22/subdir73/blk_1075202330*
> -rw-r--r-- 1 hdfs 499 3260848 Apr 27 15:02 /archive1/dn/current/BP-120244285-<ip>-1417023863606/current/finalized/subdir22/subdir73/blk_1075202330
> -rw-r--r-- 1 hdfs 499   25483 Apr 27 15:02 /archive1/dn/current/BP-120244285-<ip>-1417023863606/current/finalized/subdir22/subdir73/blk_1075202330_1484191.meta{code}
> It's worth noting that this is on HDFS tiered storage on an archive tier going to a networked
block device that may have become temporarily unavailable but is available now. See also feature
request HDFS-8297 for online rescan to not have to go around restarting datanodes.
> It turns out in the datanode log (that I am attaching) this is because the datanode fails
to get a write lock on the filesystem. I think it would be better to be able to read-only
those blocks however, since this way causes client visible data unavailability when the data
could in fact be read.
> {code}2015-04-30 14:11:08,235 WARN  datanode.DataNode (DataNode.java:checkStorageLocations(2284))
- Invalid dfs.datanode.data.dir /archive1/dn :
> org.apache.hadoop.util.DiskChecker$DiskErrorException: Directory is not writable: /archive1/dn
>         at org.apache.hadoop.util.DiskChecker.checkAccessByFileMethods(DiskChecker.java:193)
>         at org.apache.hadoop.util.DiskChecker.checkDirAccess(DiskChecker.java:174)
>         at org.apache.hadoop.util.DiskChecker.checkDir(DiskChecker.java:157)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode$DataNodeDiskChecker.checkDir(DataNode.java:2239)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode.checkStorageLocations(DataNode.java:2281)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:2263)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:2155)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:2202)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode.secureMain(DataNode.java:2378)
>         at org.apache.hadoop.hdfs.server.datanode.SecureDataNodeStarter.start(SecureDataNodeStarter.java:78)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:606)
>         at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:243)
> {code}
> Hari Sekhon
> http://www.linkedin.com/in/harisekhon
>            Reporter: Hari Sekhon
>            Priority: Critical
>         Attachments: datanode.log

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