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https://issues.apache.org/jira/browse/HADOOP-3637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12626398#action_12626398
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Allen Wittenauer commented on HADOOP-3637:
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A few folks have asked me to clarify my position on what I really want to be
able to do with snapshots.
A solution that provides a single snap of the entire file system is acceptable
for the short term. For the medium term, the solution should provide multiple
snaps of the entire file system and have them all usable simultaneously. But
ultimately, I want to be able to snapshot directories (partial file systems)
multiple times a day and have all of those snapshots available. [a la ZFS'
.zfs and NetApp's .snapshot system ] Different file paths have different
priorities with regards to a desired level of recover-ability.
I think Sanjay is correct in that snapshots will get used more for the "oops!"
situations than a full blown recovery. As an end user of other snapshot
systems, it is extremely nice being able to compare/contrast multiple versions
of the same file. This would be especially prevalent in the FUSE and NFS proxy
cases, I'd imagine, where the fs is running around in a POSIX-like costume.
I don't want to understate the need to be able to do a full file system
recovery though. Having to bring the system down just to take a snapshot is
annoying.
I want to be able to do both as they provide different solutions for different
needs. Any solution that prevents fulfilling what I need over the long haul,
to me, is probably not a good idea. I haven't dug into the spec to see if that
is the situation here.
*plink* *plink*
> 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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