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  1. Hadoop HDFS
  2. HDFS-14551

NN throws NPE if downgrade it during rolling upgrade from 3.x to 2.x

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Blocker
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
      None

      Description

      We can downgrade NN during roling upgrade (runned "hdfs dfsadmin -rollingUpgrade prepare) with HDFS-8432 involved. But with HDFS-14172 if the image has any unrecogized section, it will throw IOException at

      FSImageFormatProtobuf.java
      private void loadInternal(......) {
          ......
          String n = s.getName();
          SectionName sectionName = SectionName.fromString(n);
          if (sectionName == null) {
            throw new IOException("Unrecognized section " + n);
          }
          ......
      }
      

      and throw NPE on Hadoop 2.x

      FSImageFormatProtobuf.java
      private void loadInternal(......) {
          ......
          String n = s.getName();
          switch (sectionName)
          ......
      }
      

      When we downgrade NN from 3.x to 2.x, NN may load the image saved by 3.x NN. Then the lack of SectionName.ERASURE_CODING can break 2.x NN.
      We should just skip the unrecogized section instead of throwing exception.

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              • Assignee:
                Unassigned
                Reporter:
                John Smith Yuxuan Wang
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                Dates

                • Created:
                  Updated:
                  Resolved: