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https://issues.apache.org/jira/browse/CASSANDRA-193?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12779331#action_12779331
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Stu Hood commented on CASSANDRA-193:
------------------------------------
Here is a rebased version of the patchset which should resolve the issues found
during Jun's review.
There are significant changes in patch 4: the list of "observers" that were
waiting for valid trees to be generated was too abstract. Instead, we keep a
Cachetable of valid trees, and when an endpoint receives a tree from another
node (via TreeResponse) or generates a tree locally, it tries to 'rendezvous'
with trees from appropriate neighbors. See uses of
AntiEntropyService.register().
There is also a new patch 5 to add a manual manual repair operation to
nodeprobe, which sends out TreeRequests to all natural endpoints for the target
nodes token. The nodeprobe target is the 'initiator' for the TreeRequests, so
once the trees are generated on their respective nodes, they are broadcast out
as TreeResponses, and they will rendezvous on the target/initiator to be
differenced.
> Proactive repair
> ----------------
>
> Key: CASSANDRA-193
> URL: https://issues.apache.org/jira/browse/CASSANDRA-193
> Project: Cassandra
> Issue Type: New Feature
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Stu Hood
> Fix For: 0.5
>
> Attachments: 193-1-tree-preparation.diff,
> 193-1-tree-preparation.diff, 193-2-tree.diff, 193-2-tree.diff,
> 193-3-aes-preparation.diff, 193-3-aes-preparation.diff, 193-4-aes.diff,
> 193-4-aes.diff, 193-5-manual-repair.diff, mktree-and-binary-tree.png
>
>
> Currently cassandra supports "read repair," i.e., lazy repair when a read is
> done. This is better than nothing but is not sufficient for some cases (e.g.
> catastrophic node failure where you need to rebuild all of a node's data on a
> new machine).
> Dynamo uses merkle trees here. This is harder for Cassandra given the CF
> data model but I suppose we could just hash the serialized CF value.
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