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https://issues.apache.org/jira/browse/HDFS-2802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13490929#comment-13490929
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Eli Collins commented on HDFS-2802:
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Hey Jagane,
With regard to your first comment, the goal is definitely not to have dueling
proposals, the doc ATM posted only attempts to flesh out things in the first
proposal that were not covered or left as future work. Namely, (a) snapshot
creation time and memory usage should be O(1), and (b) consistency semantics
sufficient to implement HBase snapshots. We think these are fundamental
requirements that should be addressed in the initial design vs fixed up later;
which is why we started fleshing out a design that satisfies them, not to push
on a separate proposal. If Suresh and Nicholas now agree, which I think they
do, correct me if I'm wrong, that we should come up with a design that handles
these requirements first, rather than go with the original approach and modify
it later then I think we should merge these two design documents, which is what
ATM was attempting to do.
> Support for RW/RO snapshots in HDFS
> -----------------------------------
>
> Key: HDFS-2802
> URL: https://issues.apache.org/jira/browse/HDFS-2802
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: data-node, name-node
> Reporter: Hari Mankude
> Assignee: Hari Mankude
> Attachments: HDFS-2802.20121101.patch,
> HDFS-2802-meeting-minutes-121101.txt, HDFSSnapshotsDesign.pdf, snap.patch,
> snapshot-design.pdf, snapshot-design.tex, snapshot-one-pager.pdf,
> Snapshots20121018.pdf, Snapshots20121030.pdf
>
>
> Snapshots are point in time images of parts of the filesystem or the entire
> filesystem. Snapshots can be a read-only or a read-write point in time copy
> of the filesystem. There are several use cases for snapshots in HDFS. I will
> post a detailed write-up soon with with more information.
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