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https://issues.apache.org/jira/browse/HADOOP-3637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12628732#action_12628732
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dhruba borthakur commented on HADOOP-3637:
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Here are the suggestion modifications to my current proposal:
1. There should be an ability to specify the exclude list at snapshot creation
time. It is not enough to have a cluster-wide exclude list that apply to all
snapshot-creations.
2. The SnapNode could merge the fsimage, fsedits and exclude list to create a
single fsimage (optimization).
3. When a block is managed by the NameNode as well as the SnapNode, who manages
replication for this block? The proposal is that the SnapNode forward all
replication request to the NameNode. The NameNode can look into its blockmap to
decide whether this block really needs replication. This simplifies the
architecture because it is ways the NameNode who is the final arbitrator of
what to replicate. Similarly, if the SnapNode detects excess replicas fr a
block, it forwards the delete-excess-replica request to the NameNode. The
NameNode, based on its own blockmap, decides whether to delete the excess
replica or not.
4. This design has not impact on Namespace quotas or disk quotas. Snapshots are
created by the system administrator and has no impact on per-directory bases
disk quotas.
> 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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