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Posted to hdfs-issues@hadoop.apache.org by "Sanjay Radia (Commented) (JIRA)" <ji...@apache.org> on 2011/10/18 23:35:10 UTC
[jira] [Commented] (HDFS-1971) HA: Send block report from datanode
to both active and standby namenodes
[ https://issues.apache.org/jira/browse/HDFS-1971?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13130037#comment-13130037 ]
Sanjay Radia commented on HDFS-1971:
------------------------------------
I have attached a partial patch.
* I have created a BPServiceToStandby class as a subclass of the BPOfferService class. However, I think I need to revisit this. The reason is that when NN failover occurs the thread that sends the BRs to standby should perform the same function as the main BPOfferService thread; we don't want to start a new BPOfferService since it will have to reregister and send new block reports. Hence I believe that I am thinking of simply adding a state to BPOfferService. Will post an updated patch.
* The block-additions-deletions are passed from the primary BP thread to the secondary BP thread.
* The patch generates the BRs again. The code can be easily modified to optimize for option 1 or option 3.
** @eli - double-scanning DN disks ... Note for BRs we do not scan the disks but instead generate the BR from the Block-map data structure.
> HA: Send block report from datanode to both active and standby namenodes
> ------------------------------------------------------------------------
>
> Key: HDFS-1971
> URL: https://issues.apache.org/jira/browse/HDFS-1971
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: data-node, name-node
> Reporter: Suresh Srinivas
> Assignee: Sanjay Radia
> Attachments: DualBlockReports.pdf, daulBr1.patch
>
>
> To enable hot standby namenode, the standby node must have current information for - namenode state (image + edits) and block location information. This jira addresses keeping the block location information current in the standby node. To do this, the proposed solution is to send block reports from the datanodes to both the active and the standby namenode.
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