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From "Raghu Angadi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4663) Datanode should delete files under tmp when upgraded from 0.17
Date Wed, 28 Jan 2009 23:28:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12668232#action_12668232
] 

Raghu Angadi commented on HADOOP-4663:
--------------------------------------

> The primary datanode then stamps all those "valid" replicas with a new generation stamp
and updates the namenode inode list with this new generation stamp for this block.

Thanks that is useful. I am still trying deduce whether you are implying there will be a corruption
or a valid replica.

As I see it, in this case there will be one replica with 'x+5' bytes with the new gen-stamp.
But given that checksum does not match (no sync to native filesystem is done, all three datanodes
are killed while they are in wrte() system call), looks like we end up with corruption.. right?
I am missing something?

> Datanode should delete files under tmp when upgraded from 0.17
> --------------------------------------------------------------
>
>                 Key: HADOOP-4663
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4663
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.18.0
>            Reporter: Raghu Angadi
>            Assignee: dhruba borthakur
>            Priority: Blocker
>             Fix For: 0.19.1
>
>         Attachments: deleteTmp.patch, deleteTmp2.patch, deleteTmp_0.18.patch, handleTmp1.patch
>
>
> Before 0.18, when Datanode restarts, it deletes files under data-dir/tmp  directory since
these files are not valid anymore. But in 0.18 it moves these files to normal directory incorrectly
making them valid blocks. One of the following would work :
> - remove the tmp files during upgrade, or
> - if the files under /tmp are in pre-18 format (i.e. no generation), delete them.
> Currently effect of this bug is that, these files end up failing block verification and
eventually get deleted. But cause incorrect over-replication at the namenode before that.
> Also it looks like our policy regd treating files under tmp needs to be defined better.
Right now there are probably one or two more bugs with it. Dhruba, please file them if you
rememeber.

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