[jira] Updated: (HDFS-142) Datanode should delete files under tmp when upgraded from 0.17

["Todd Lipcon (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDFS-142?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Todd Lipcon updated HDFS-142:
-----------------------------

    Attachment: testfileappend4-deaddn.txt

I found a bug in the append code where it doesn't work properly with the following sequence:
- open a file for write
- write some data
- close it
- the DN with the lowest name dies, but not yet marked dead on the NN
- a client calls append() to try to recover the lease (not knowing that the file isn't currently under construction)

In this case, the client ends up thinking it has opened the file for append, and there's a new lease on the NN side, but on the client side it's in an error state where close() will throw IOE (and not close the new lease).

Attaching a new case for TestFileAppend4 for this situation.

> Datanode should delete files under tmp when upgraded from 0.17
> --------------------------------------------------------------
>
>                 Key: HDFS-142
>                 URL: https://issues.apache.org/jira/browse/HDFS-142
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Raghu Angadi
>            Assignee: dhruba borthakur
>            Priority: Blocker
>         Attachments: appendQuestions.txt, deleteTmp.patch, deleteTmp2.patch, deleteTmp5_20.txt, deleteTmp5_20.txt, deleteTmp_0.18.patch, handleTmp1.patch, hdfs-142-minidfs-fix-from-409.txt, HDFS-142-multiple-blocks-datanode-exception.patch, HDFS-142_20.patch, testfileappend4-deaddn.txt
>
>
> 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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