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https://issues.apache.org/jira/browse/HADOOP-3637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12626371#action_12626371
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Sanjay Radia commented on HADOOP-3637:
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My comment is regarding the motivation for snapshots as described here.
The introduction of the attached file states that the motivation is timetravel
to previous states of the file system.
Clearly HDFS can store data over time and store an evolving state of some data
in different files with name and timestamps. Is this not sufficient? Or are you
really looking for a way to look at the complete file system view at particular
point in time.
Snapshots in other systems are motivated by recovering accidental deletions or
changes.
Also this design proposes snapshotting the entire file system rather then some
subtree.
I suspect that for backup purposes, one wants to snapshot different parts of
the file system at different degrees of granularity (rather then the filesystem
as a whole).
> Support for snapshots
> ---------------------
>
> Key: HADOOP-3637
> URL: https://issues.apache.org/jira/browse/HADOOP-3637
> Project: Hadoop Core
> Issue Type: New Feature
> Components: dfs
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: Snapshots.pdf, Snapshots.pdf
>
>
> Support HDFS snapshots. It should support creating snapshots without shutting
> down the file system. Snapshot creation should be lightweight and a typical
> system should be able to support a few thousands concurrent snapshots. There
> should be a way to surface (i.e. mount) a few of these snapshots
> simultaneously.
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