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https://issues.apache.org/jira/browse/HDFS-13709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16906329#comment-16906329
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Stephen O'Donnell commented on HDFS-13709:
------------------------------------------
[~jojochuang] pointed me to this Jira as I am working on the related one in
HDFS-14706. I just have on minor comment here. In your definition of the new
exception class "DiskFileCorruptException", if you add a method like:
{code:java}
public DiskFileCorruptException(String msg, Throwable cause) {
super(msg, cause);
}{code}
Then you can avoid having to adjust the stack trace etc when you create this
exception, so you can change this:
{code:java}
+ if (ioe.getMessage().startsWith(EIO_ERROR)) {
+ DiskFileCorruptException de = new DiskFileCorruptException("Original
Exception : " + ioe);
+ de.initCause(ioe);
+ de.setStackTrace(ioe.getStackTrace());
+ throw de;
+ }{code}
To just this:
{code:java}
if (ioe.getMessage().startsWith(EIO_ERROR)) {
throw new DiskFileCorruptException("A disk IO error occurred", ioe);
}{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.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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