[jira] Commented: (HADOOP-855) HDFS should repair corrupted files

["Doug Cutting (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12462257 ] 

Doug Cutting commented on HADOOP-855:
-------------------------------------

Mostly this sounds good to me.

> 1. change reportChecksumFailure parameter crc from int to FSInputStream

I'm confused by this one.  There's already an FSInputStream parameter.  In the DistributedFileSystem implementation of this method, one can cast this to DFSInputStream and then access whatever implementation-specific state is needed (like the datanode where the block in question resides).  So I see no need to alter the reportChecksumFailure signature.


> HDFS should repair corrupted files
> ----------------------------------
>
>                 Key: HADOOP-855
>                 URL: https://issues.apache.org/jira/browse/HADOOP-855
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>            Reporter: Wendy Chien
>         Assigned To: Wendy Chien
>
> While reading if we discover a mismatch between a block and checksum, we want to report this back to the namenode to delete the corrupted block or crc.
> To implement this, we need to do the following:
> DFSInputStream
> 1. move DFSInputStream out of DFSClient
> 2. add member variable to keep track of current datanode (the chosen node)
> DistributedFileSystem
> 1. change reportChecksumFailure parameter crc from int to FSInputStream (needed to be able to delete it). 
> 2. determine specific block and datanode from DFSInputStream passed to reportChecksumFailure  
> 3. call namenode to delete block/crc vis DFSClient
> ClientProtocol
> 1. add method to ask namenode to delete certain blocks on specifc datanode.
> Namenode
> 1. add ability to delete certain blocks on specific datanode

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