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https://issues.apache.org/jira/browse/HDDS-935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16746710#comment-16746710
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Mukul Kumar Singh commented on HDDS-935:
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Thanks for working on this [~shashikant]. The code generally looks good to me.
1) Can StateMachine create an output stream and pass it to the dispatcher. In
the current code, there are 2 file operations 1) create File and 2) second one
to write container info to the file. This can be avoided by passing the output
stream to the dispatcher.
2) There are some unused import which can be removed.
> Avoid creating an already created container on a datanode in case of disk
> removal followed by datanode restart
> --------------------------------------------------------------------------------------------------------------
>
> Key: HDDS-935
> URL: https://issues.apache.org/jira/browse/HDDS-935
> Project: Hadoop Distributed Data Store
> Issue Type: Improvement
> Components: Ozone Datanode
> Affects Versions: 0.4.0
> Reporter: Rakesh R
> Assignee: Shashikant Banerjee
> Priority: Major
> Attachments: HDDS-935.000.patch
>
>
> Currently, a container gets created when a writeChunk request comes to
> HddsDispatcher and if the container does not exist already. In case a disk on
> which a container exists gets removed and datanode restarts and now, if a
> writeChunkRequest comes , it might end up creating the same container again
> with an updated BCSID as it won't detect the disk is removed. This won't be
> detected by SCM as well as it will have the latest BCSID. This Jira aims to
> address this issue.
> The proposed fix would be to persist the all the containerIds existing in the
> containerSet when a ratis snapshot is taken in the snapshot file. If the disk
> is removed and dn gets restarted, the container set will be rebuild after
> scanning all the available disks and the the container list stored in the
> snapshot file will give all the containers created in the datanode. The diff
> between these two will give the exact list of containers which were created
> but were not detected after the restart. Any writeChunk request now should
> validate the container Id from the list of missing containers. Also, we need
> to ensure container creation does not happen as part of applyTransaction of
> writeChunk request in Ratis.
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