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https://issues.apache.org/jira/browse/CASSANDRA-4123?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401659#comment-13401659
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Jonathan Ellis commented on CASSANDRA-4123:
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bq. A better solution would be to add an extra level of hierarchy to NTS so
that it still supported DC & rack, and IP would be the new level at the bottom
of the hierarchy
Agreed--with the caveat that if we don't have enough racks to satisfy the
replica count, we shrug and throw multiple replicas on a rack. But if we don't
have enough hosts, I think that should be fatal (as it is now, in the
vnode-less world).
> vnodes aware Replication Strategy
> ----------------------------------
>
> Key: CASSANDRA-4123
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4123
> Project: Cassandra
> Issue Type: Sub-task
> Components: Core
> Reporter: Sam Overton
> Assignee: Sam Overton
>
> The simplest implementation for this would be if NTS regarded a single host
> as a distinct rack. This would prevent replicas being placed on the same
> host. The rest of the logic for replica selection would be identical to NTS
> (but this would be removing a level of topology hierarchy). This would be
> achievable just by writing a snitch to place hosts in their own rack.
> A better solution would be to add an extra level of hierarchy to NTS so that
> it still supported DC & rack, and IP would be the new level at the bottom of
> the hierarchy. The logic would remain largely the same.
> I would very much like to build in Peter Schuller's notion of Distribution
> Factor (as described in
> http://www.mail-archive.com/[email protected]/msg03844.html). This
> requires a method of defining a "replica set" for each host and then treating
> it in a similar way to a DC (ie. RF replicas are chosen from that set,
> instead of from the whole cluster).
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