Mithun Radhakrishnan created MAPREDUCE-5065: -----------------------------------------------
Summary: DistCp should skip checksum comparisons if block-sizes are different on source/target. Key: MAPREDUCE-5065 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5065 Project: Hadoop Map/Reduce Issue Type: Bug Components: distcp Affects Versions: 0.23.5, 2.0.3-alpha Reporter: Mithun Radhakrishnan Assignee: Mithun Radhakrishnan When copying files between 2 clusters with different default block-sizes, one sees that the copy fails with a checksum-mismatch, even though the files have identical contents. The reason is that on HDFS, a file's checksum is unfortunately a function of the block-size of the file. So you could have 2 different files with identical contents (but different block-sizes) have different checksums. (Thus, it's also possible for DistCp to fail to copy files on the same file-system, if the source-file's block-size differs from HDFS default, and -pb isn't used.) I propose that we skip checksum comparisons under the following conditions: 1. -skipCrc is specified. 2. File-size is 0 (in which case the call to the checksum-servlet is moot). 3. source.getBlockSize() != target.getBlockSize(), since the checksums are guaranteed to differ in this case. I have a patch for #3. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira