Details

    • Type: New Feature New Feature
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.14.0
    • Component/s: None
    • Labels:
      None

      Description

      Currently CRCs are handled at FileSystem level and are transparent to core HDFS. See recent improvement HADOOP-928 ( that can add checksums to a given filesystem ) regd more about it. Though this served us well there a few disadvantages :

      1) This doubles namespace in HDFS ( or other filesystem implementations ). In many cases, it nearly doubles the number of blocks. Taking namenode out of CRCs would nearly double namespace performance both in terms of CPU and memory.

      2) Since CRCs are transparent to HDFS, it can not actively detect corrupted blocks. With block level CRCs, Datanode can periodically verify the checksums and report corruptions to namnode such that name replicas can be created.

      We propose to have CRCs maintained for all HDFS data in much the same way as in GFS. I will update the jira with detailed requirements and design. This will include same guarantees provided by current implementation and will include a upgrade of current data.

      1. BlockCrcFeatureTestPlan.pdf
        19 kB
        Raghu Angadi
      2. DfsBlockCrcDesign.htm
        21 kB
        Raghu Angadi
      3. HADOOP-1134-03.patch
        203 kB
        Raghu Angadi
      4. HADOOP-1134-02.patch
        203 kB
        Raghu Angadi
      5. HADOOP-1134-01.patch
        189 kB
        Raghu Angadi
      6. BlockLevelCrc-07122007.patch
        193 kB
        Raghu Angadi
      7. BlockLevelCrc-07102007.patch
        186 kB
        Raghu Angadi
      8. BlockLevelCrc-07062007.patch
        177 kB
        Raghu Angadi
      9. BlockLevelCrc-07052007.patch
        178 kB
        Raghu Angadi
      10. BlockLevelCrc-07032007.patch
        168 kB
        Raghu Angadi
      11. readBuffer.java
        1.0 kB
        Raghu Angadi

        Issue Links

          Activity

          No work has yet been logged on this issue.

            People

            • Assignee:
              Raghu Angadi
              Reporter:
              Raghu Angadi
            • Votes:
              0 Vote for this issue
              Watchers:
              2 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:

                Development