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https://issues.apache.org/jira/browse/HDFS-13709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16909643#comment-16909643
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Wei-Chiu Chuang commented on HDFS-13709:
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Thanks [~zhangchen]
Can you help verify the failed tests are unrelated?
Additionally, it would be great if you can add a few javadoc comments for the
new handleBadBlock() method. Its logic can be a little convoluted given that
there are two asynchronous threads involved (datanode and volume scanner) We
definitely want to avoid a situation where volumescanner finds a suspect,
calling handleBadBlock() and then the suspect is put into voumescanner's queue
and get scanned again and again non-stop.
nit
{code:java}
assertTrue(replicaCount == 1);
{code}
better to use
{code:java}
assertEquals("error message", 1, replicaCount);
{code}
> Report bad block to NN when transfer block encounter EIO exception
> ------------------------------------------------------------------
>
> Key: HDFS-13709
> URL: https://issues.apache.org/jira/browse/HDFS-13709
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Reporter: Chen Zhang
> Assignee: Chen Zhang
> Priority: Major
> Attachments: HDFS-13709.002.patch, HDFS-13709.003.patch,
> HDFS-13709.004.patch, HDFS-13709.patch
>
>
> In our online cluster, the BlockPoolSliceScanner is turned off, and sometimes
> disk bad track may cause data loss.
> For example, there are 3 replicas on 3 machines A/B/C, if a bad track occurs
> on A's replica data, and someday B and C crushed at the same time, NN will
> try to replicate data from A but failed, this block is corrupt now but no one
> knows, because NN think there is at least 1 healthy replica and it keep
> trying to replicate it.
> When reading a replica which have data on bad track, OS will return an EIO
> error, if DN reports the bad block as soon as it got an EIO, we can find
> this case ASAP and try to avoid data loss
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