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From "stanley shi (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-6489) DFS Used space is not correct computed on frequent append operations
Date Thu, 05 Jun 2014 07:33:01 GMT

     [ https://issues.apache.org/jira/browse/HDFS-6489?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

stanley shi updated HDFS-6489:
------------------------------

    Summary: DFS Used space is not correct computed on frequent append operations  (was: DFS
Used space is not correct if there're many append operations)

> DFS Used space is not correct computed on frequent append operations
> --------------------------------------------------------------------
>
>                 Key: HDFS-6489
>                 URL: https://issues.apache.org/jira/browse/HDFS-6489
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode
>    Affects Versions: 2.2.0
>            Reporter: stanley shi
>
> The current implementation of the Datanode will increase the DFS used space on each block
write operation. This is correct in most scenario (create new file), but sometimes it will
behave in-correct(append small data to a large block).
> For example, I have a file with only one block(say, 60M). Then I try to append to it
very frequently but each time I append only 10 bytes;
> Then on each append, dfs used will be increased with the length of the block(60M), not
teh actual data length(10bytes).
> Consider in a scenario I use many clients to append concurrently to a large number of
files (1000+), assume the block size is 32M (half of the default value), then the dfs used
will be increased 1000*32M = 32G on each append to the files; but actually I only write 10K
bytes; this will cause the datanode to report in-sufficient disk space on data write.
> {quote}2014-06-04 15:27:34,719 INFO org.apache.hadoop.hdfs.server.datanode.DataNode:
opWriteBlock
>  BP-1649188734-10.37.7.142-1398844098971:blk_1073742834_45306 received exception org.apach
> e.hadoop.util.DiskChecker$DiskOutOfSpaceException: Insufficient space for appending to
Fin
> alizedReplica, blk_1073742834_45306, FINALIZED{quote}



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