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https://issues.apache.org/jira/browse/HDFS-13056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16433401#comment-16433401
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Hudson commented on HDFS-13056:
-------------------------------
SUCCESS: Integrated in Jenkins build Hadoop-trunk-Commit #13966 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/13966/])
HDFS-13056. Expose file-level composite CRCs in HDFS which are (xiao: rev
7c9cdad6d04c98db5a83e2108219bf6e6c903daf)
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileChecksum.java
* (add)
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/CrcUtil.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/impl/DfsClientConf.java
* (add)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/BlockChecksumType.java
* (add)
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestCrcUtil.java
* (add)
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestCrcComposer.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/fs/Hdfs.java
* (add)
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileChecksumCompositeCrc.java
* (add)
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CompositeCrcFileChecksum.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockChecksumHelper.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocolPB/TestPBHelper.java
* (edit)
hadoop-tools/hadoop-distcp/src/test/java/org/apache/hadoop/tools/mapred/TestCopyMapper.java
* (add)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/BlockChecksumOptions.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocolPB/PBHelperClient.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/FileChecksumHelper.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/DFSTestUtil.java
* (edit) hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtocol.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/datatransfer.proto
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Receiver.java
* (add)
hadoop-tools/hadoop-distcp/src/test/java/org/apache/hadoop/tools/mapred/TestCopyMapperCompositeCrc.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataXceiver.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockChecksumReconstructor.java
* (edit)
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/Options.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
* (add)
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/CrcComposer.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockReconstructor.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java
* (edit)
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DataChecksum.java
* (add)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockChecksumCompositeCrcReconstructor.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java
* (edit) hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/hdfs.proto
* (add)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockChecksumMd5CrcReconstructor.java
> Expose file-level composite CRCs in HDFS which are comparable across
> different instances/layouts
> ------------------------------------------------------------------------------------------------
>
> Key: HDFS-13056
> URL: https://issues.apache.org/jira/browse/HDFS-13056
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: datanode, distcp, erasure-coding, federation, hdfs
> Affects Versions: 3.0.0
> Reporter: Dennis Huo
> Assignee: Dennis Huo
> Priority: Major
> Fix For: 3.2.0
>
> Attachments: HDFS-13056-branch-2.8.001.patch,
> HDFS-13056-branch-2.8.002.patch, HDFS-13056-branch-2.8.003.patch,
> HDFS-13056-branch-2.8.004.patch, HDFS-13056-branch-2.8.005.patch,
> HDFS-13056-branch-2.8.poc1.patch, HDFS-13056.001.patch, HDFS-13056.002.patch,
> HDFS-13056.003.patch, HDFS-13056.003.patch, HDFS-13056.004.patch,
> HDFS-13056.005.patch, HDFS-13056.006.patch, HDFS-13056.007.patch,
> HDFS-13056.008.patch, HDFS-13056.009.patch, HDFS-13056.010.patch,
> HDFS-13056.011.patch, HDFS-13056.012.patch, HDFS-13056.013.patch,
> HDFS-13056.014.patch, Reference_only_zhen_PPOC_hadoop2.6.X.diff,
> hdfs-file-composite-crc32-v1.pdf, hdfs-file-composite-crc32-v2.pdf,
> hdfs-file-composite-crc32-v3.pdf
>
>
> FileChecksum was first introduced in
> [https://issues-test.apache.org/jira/browse/HADOOP-3981] and ever since then
> has remained defined as MD5-of-MD5-of-CRC, where per-512-byte chunk CRCs are
> already stored as part of datanode metadata, and the MD5 approach is used to
> compute an aggregate value in a distributed manner, with individual datanodes
> computing the MD5-of-CRCs per-block in parallel, and the HDFS client
> computing the second-level MD5.
>
> A shortcoming of this approach which is often brought up is the fact that
> this FileChecksum is sensitive to the internal block-size and chunk-size
> configuration, and thus different HDFS files with different block/chunk
> settings cannot be compared. More commonly, one might have different HDFS
> clusters which use different block sizes, in which case any data migration
> won't be able to use the FileChecksum for distcp's rsync functionality or for
> verifying end-to-end data integrity (on top of low-level data integrity
> checks applied at data transfer time).
>
> This was also revisited in https://issues.apache.org/jira/browse/HDFS-8430
> during the addition of checksum support for striped erasure-coded files;
> while there was some discussion of using CRC composability, it still
> ultimately settled on hierarchical MD5 approach, which also adds the problem
> that checksums of basic replicated files are not comparable to striped files.
>
> This feature proposes to add a "COMPOSITE-CRC" FileChecksum type which uses
> CRC composition to remain completely chunk/block agnostic, and allows
> comparison between striped vs replicated files, between different HDFS
> instances, and possible even between HDFS and other external storage systems.
> This feature can also be added in-place to be compatible with existing block
> metadata, and doesn't need to change the normal path of chunk verification,
> so is minimally invasive. This also means even large preexisting HDFS
> deployments could adopt this feature to retroactively sync data. A detailed
> design document can be found here:
> https://storage.googleapis.com/dennishuo/hdfs-file-composite-crc32-v1.pdf
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