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https://issues.apache.org/jira/browse/HDFS-8828?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yufei Gu updated HDFS-8828:
---------------------------
Description:
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.
was:
Some users reported huge time cost to build file copy list in distcp. (30 hours
with 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 copy list
which will traverse all files under the source dir. This patch will build the
copy list based on snapshot diff report.
> 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
>
>
> 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.
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