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https://issues.apache.org/jira/browse/HDFS-10301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15347427#comment-15347427
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Vinitha Reddy Gankidi commented on HDFS-10301:
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Thanks for the review Colin. I have addressed your comments below:
{quote}
This won't work in the presence of reordered RPCs. If the RPCs are reordered so
that curRpc 1 arrives before curRpc 0, the lease will be removed and RPC 0 will
be rejected.
{quote}
If curRpc 1 arrives before curRpc 0, the lease will be removed and
{{node.leaseId}} will be set to zero. I have modified BlockReportLeaseManager
to return true when {{node.leaseId = 0}}. I explained the same in my previous
comment:
https://issues.apache.org/jira/browse/HDFS-10301?focusedCommentId=15299255&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15299255
Please let me know if you see any issues with this approach.
{quote}
Using object equality to compare two BlockListAsLongs objects is very
surprising to anyone reading the code.
{quote}
I uploaded a new patch (007) to address this issue. I have added a method
{{isStorageReportOnly()}} to BlockListsAsLongs that returns true only for
STORAGE_REPORT_ONLY BlockListsAsLong.
In the upgrade case, there is no way to detect the zombie storages since the
old DNs do not send the information about the storages in the BR in the last
RPC. In practice, hot-swapping of DN drives and upgrading the DN may not happen
at the same time.
> BlockReport retransmissions may lead to storages falsely being declared
> zombie if storage report processing happens out of order
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-10301
> URL: https://issues.apache.org/jira/browse/HDFS-10301
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.6.1
> Reporter: Konstantin Shvachko
> Assignee: Vinitha Reddy Gankidi
> Priority: Critical
> Attachments: HDFS-10301.002.patch, HDFS-10301.003.patch,
> HDFS-10301.004.patch, HDFS-10301.005.patch, HDFS-10301.006.patch,
> HDFS-10301.01.patch, HDFS-10301.sample.patch, zombieStorageLogs.rtf
>
>
> When NameNode is busy a DataNode can timeout sending a block report. Then it
> sends the block report again. Then NameNode while process these two reports
> at the same time can interleave processing storages from different reports.
> This screws up the blockReportId field, which makes NameNode think that some
> storages are zombie. Replicas from zombie storages are immediately removed,
> causing missing blocks.
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