[jira] [Resolved] (HDDS-10681) EC Reconstruction does not issue put block to data index if it is unused

["Stephen O'Donnell (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDDS-10681?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stephen O'Donnell resolved HDDS-10681.
--------------------------------------
    Fix Version/s: 1.5.0
       Resolution: Fixed

> EC Reconstruction does not issue put block to data index if it is unused
> ------------------------------------------------------------------------
>
>                 Key: HDDS-10681
>                 URL: https://issues.apache.org/jira/browse/HDDS-10681
>             Project: Apache Ozone
>          Issue Type: Bug
>            Reporter: Stephen O'Donnell
>            Assignee: Stephen O'Donnell
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.5.0
>
>
> Given a small EC block:
> * <= 2MB for EC-3-2
> * <= 5MB for EC-6-3
> * <= 9MB for EC-10-4
> So that it is less than a full stripe and does not use all the datanodes.
> When reconstruction happens to replace a replica which is not used in the stripe, the unused containers are not issued with the put block to store the details of the empty block within the container. Note that the container replica will likely have other blocks, so it will still get reconstructed, but it will not be given a reference to this empty block.
> All containers are checked for the presence of all blocks during reconstruction. If any of the containers do not have a reference to the block, it is considered an orphan block / abandoned stripe and will not be reconstructed.
> Therefore if one replica has no entry for the block, then it is used it another reconstruction for another replica later, that block will not get reconstructed into a second replica. Over time this can result in the reference getting removed from all copies.



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