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https://issues.apache.org/jira/browse/HDFS-4103?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz Wo (Nicholas), SZE updated HDFS-4103:
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Description:
In our first snapshot implementation, snapshot creation runs in O(N) and
occupies O(N) memory space, where N = # files + # directories + # symlinks in
the snapshot. The advantages of the implementation are that there is no
additional cost for the modifications after snapshots are created, and it leads
to a simple implementation.
In this JIRA, we optimize snapshot creation to O(1) although it introduces
additional cost in the modifications after snapshots are created. Note that
the INode is given as an assumption, otherwise, there is a non-constant cost to
find the INode.
was:
In our first snapshot implementation, snapshot creation runs in O(N) and
occupies O(N) memory space, where N = # files + # directories + # symlinks in
the snapshot. The advantages of the implementation are that there is no
additional cost for the modifications after snapshots are created, and it leads
to a simple implementation.
In this JIRA, we optimize snapshot creation to O(1) although it introduces
additional cost in the modifications after snapshots are created.
> Support O(1) snapshot creation
> ------------------------------
>
> Key: HDFS-4103
> URL: https://issues.apache.org/jira/browse/HDFS-4103
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
> Attachments: h4103_20121129.patch
>
>
> In our first snapshot implementation, snapshot creation runs in O(N) and
> occupies O(N) memory space, where N = # files + # directories + # symlinks in
> the snapshot. The advantages of the implementation are that there is no
> additional cost for the modifications after snapshots are created, and it
> leads to a simple implementation.
> In this JIRA, we optimize snapshot creation to O(1) although it introduces
> additional cost in the modifications after snapshots are created. Note that
> the INode is given as an assumption, otherwise, there is a non-constant cost
> to find the INode.
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