ASF GitHub Bot logged work on HDDS-1843:

                Author: ASF GitHub Bot
            Created on: 06/Sep/19 11:25
            Start Date: 06/Sep/19 11:25
    Worklog Time Spent: 10m 
      Work Description: bshashikant commented on pull request #1364: HDDS-1843. 
Undetectable corruption after restart of a datanode.
URL: https://github.com/apache/hadoop/pull/1364
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Issue Time Tracking

    Worklog Id:     (was: 307767)
    Time Spent: 9h 20m  (was: 9h 10m)

> Undetectable corruption after restart of a datanode
> ---------------------------------------------------
>                 Key: HDDS-1843
>                 URL: https://issues.apache.org/jira/browse/HDDS-1843
>             Project: Hadoop Distributed Data Store
>          Issue Type: Bug
>          Components: Ozone Datanode
>    Affects Versions: 0.5.0
>            Reporter: Shashikant Banerjee
>            Assignee: Shashikant Banerjee
>            Priority: Critical
>              Labels: pull-request-available
>             Fix For: 0.5.0
>         Attachments: HDDS-1843.000.patch
>          Time Spent: 9h 20m
>  Remaining Estimate: 0h
> Right now, all write chunks use BufferedIO ie, sync flag is disabled by 
> default. Also, Rocks Db metadata updates are done in Rocks DB cache first at 
> Datanode. In case, there comes a situation where the buffered chunk data as 
> well as the corresponding metadata update is lost as a part of datanode 
> restart, it may lead to a situation where, it will not be possible to detect 
> the corruption (not even with container scanner) of this nature in a 
> reasonable time frame, until and unless there is a client IO failure or Recon 
> server detects it over time. In order to atleast to detect the problem, Ratis 
> snapshot on datanode should sync the rocks db file . In such a way, 
> ContainerScanner will be able to detect this.We can also add a metric around 
> sync to measure how much of a throughput loss it can incurr.
> Thanks [~msingh] for suggesting this.

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