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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 22:56:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12668208#action_12668208
] 

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

bq. @Raghu: The hard-limit-lease-timeout is currently one hour. The NN will start lease recovery
after 1 hour. The lease recovery process locates the right replicas (with the same size) bumps
up the generation stamp on all these datanode(s), and persists the new block id (that has
the new generation stamp) into the Inode. Since the inode map now has a new block id (because
of the change in gen stamp), all old replicas that have the old generation stamp do not belong
to any inode. If such a old block checks in with the NN via a block report, it will get deleted.
Does it sound right? 

>From the scenario I outlined above, will it work? All the blocks have same gen-stamp and
have (slightly) different lengths. For the given scenario above, could you tell how it ends
up with a valid block? Sorry you might have already answered in above comment.. but I could
not easily see it.

> 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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