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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4663) Datanode should delete files under tmp when upgraded from 0.17
Date Thu, 29 Jan 2009 00:16:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12668255#action_12668255
] 

dhruba borthakur commented on HADOOP-4663:
------------------------------------------

An offline discussion with Raghu resulted in this proposal (slight modification to Hairong's
proposal):

The Datanode, on startup, verifies the length of each block in the "blocksBeingWrtitten" directory
with their corresponding meta files lengths (and truncates block file is necessary to match
meta file). It inserts these blocks in ongoingCreates.It then leaves those blocks for the
lease recovery process to prompt them.  A block report does not contain this block, but it
is ok. The NN block report processing always ignores the last block of a file under construction.


> 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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