Uploaded image for project: 'Hadoop HDFS'
  1. Hadoop HDFS
  2. HDFS-11833

HDFS architecture documentation describes outdated placement policy

Log workAgile BoardRank to TopRank to BottomAttach filesAttach ScreenshotBulk Copy AttachmentsBulk Move AttachmentsVotersWatch issueWatchersCreate sub-taskConvert to sub-taskMoveLinkCloneLabelsUpdate Comment AuthorReplace String in CommentUpdate Comment VisibilityDelete Comments
    XMLWordPrintableJSON

Details

    • Reviewed

    Description

      Hello

      I've noticed inconsistencies in the default block placement policy between what one can read on several websites and what is stated in the official documentation.

      After digging, I've found out that the proper default placement policy is :

       * The replica placement strategy is that if the writer is on a datanode,
       * the 1st replica is placed on the local machine, 
       * otherwise a random datanode. The 2nd replica is placed on a datanode
       * that is on a different rack. The 3rd replica is placed on a datanode
       * which is on a different node of the rack as the second replica.
       

      source

      HADOOP-5734 has been opened regarding this mistake several years ago and has eventually been merged but unfortunately this fix has been overwritten by Alejandro Abdelnur in SVN commit.

      dud

      Attachments

        Activity

          This comment will be Viewable by All Users Viewable by All Users
          Cancel

          People

            vagarychen Chen Liang Assign to me
            dud dud
            Votes:
            0 Vote for this issue
            Watchers:
            5 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved:

              Slack

                Issue deployment