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Yufei Gu commented on HDFS-8828: -------------------------------- Hi Yongjun, Thank you very much for detailed code review and all nice suggestion. I've upload a new patch(HDFS-8828.003.path) for above comments. > Utilize Snapshot diff report to build copy list in distcp > --------------------------------------------------------- > > Key: HDFS-8828 > URL: https://issues.apache.org/jira/browse/HDFS-8828 > Project: Hadoop HDFS > Issue Type: Improvement > Components: distcp, snapshots > Reporter: Yufei Gu > Assignee: Yufei Gu > Attachments: HDFS-8828.001.patch, HDFS-8828.002.patch, > HDFS-8828.003.patch > > > Some users reported huge time cost to build file copy list in distcp. (30 > hours for 1.6M files). We can leverage snapshot diff report to build file > copy list including files/dirs which are changes only between two snapshots > (or a snapshot and a normal dir). It speed up the process in two folds: 1. > less copy list building time. 2. less file copy MR jobs. > HDFS snapshot diff report provide information about file/directory creation, > deletion, rename and modification between two snapshots or a snapshot and a > normal directory. HDFS-7535 synchronize deletion and rename, then fallback to > the default distcp. So it still relies on default distcp to building complete > list of files under the source dir. This patch only puts creation and > modification files into the copy list based on snapshot diff report. We can > minimize the number of files to copy. -- This message was sent by Atlassian JIRA (v6.3.4#6332)