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Posted to common-dev@hadoop.apache.org by "Raghu Angadi (JIRA)" <ji...@apache.org> on 2007/10/16 22:14:51 UTC
[jira] Commented: (HADOOP-2065) Replication policy for corrupted
block
[ https://issues.apache.org/jira/browse/HADOOP-2065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12535332 ]
Raghu Angadi commented on HADOOP-2065:
--------------------------------------
#2 above will be handled in HADOOP-2012. When it detects a corrupt block, it just asks the Namenode to delete it (same interface is used by client when it detects a bad block). In this case, namenode deletes the block as long as there are more replicas. So it does not really make sure that there is at least one _good_ replica.
> Replication policy for corrupted block
> ---------------------------------------
>
> Key: HADOOP-2065
> URL: https://issues.apache.org/jira/browse/HADOOP-2065
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.14.1
> Reporter: Koji Noguchi
>
> Thanks to HADOOP-1955, even if one of the replica is corrupted, the block should get replicated from a good replica relatively fast.
> Created this ticket to continue the discussion from http://issues.apache.org/jira/browse/HADOOP-1955#action_12531162.
> bq. 2. Delete corrupted source replica
> bq. 3. If all replicas are corrupt, stop replication.
> For (2), it'll be nice if the namenode can delete the corrupted block if there's a good replica on other nodes.
> For (3), I prefer if the namenode can still replicate the block.
> Before 0.14, if the file was corrupted, users were still able to pull the data and decide if they want to delete those files. (HADOOP-2063)
> In 0.14 and later, we cannot/don't replicate these blocks so they eventually get lost.
> To make the matters worse, if the corrupted file is accessed, all the corrupted replicas would be deleted except for one and stay as replication factor of 1 forever.
>
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