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From Vijay <vijay2...@gmail.com>
Subject Re: RFC: Cassandra Virtual Nodes
Date Tue, 20 Mar 2012 02:37:14 GMT
I also did create a ticket
https://issues.apache.org/jira/browse/CASSANDRA-3768 with some of the
reason why I would like to see vnodes in cassandra.
It can also potentially reduce the SSTable seeks which a node has to do to
query data in SizeTireCompaction if extended to the filesystem.

But 110% agree with Peter, we need to take incremental steps and start with
the existing bootstrapping.
May be we can start it by making a set of Ranges/Token to a node insted of
one token. And then may be building things around the movement of those
ranges.

I have been thinking about this for a while but having trouble to get to a
point where i am comfortable changing big chunks of code.

Regards,
</VJ>



On Mon, Mar 19, 2012 at 4:45 PM, Peter Schuller <peter.schuller@infidyne.com
> wrote:

> (I may comment on other things more later)
>
> > As a side note: vnodes fail to provide solutions to node-based
> limitations
> > that seem to me to cause a substantial portion of operational issues such
> > as impact of node restarts / upgrades, GC and compaction induced
> latency. I
>
> Actually, it does. At least assumign DF > RF (as in the original
> proposal, and mine). The impact of a node suffering from a performance
> degradation is mitigated because the effects are spread out over DF-1
> (N-1 in the original post) nodes instead of just RF nodes.
>
> > think some progress could be made here by allowing a "pack" of
> independent
> > Cassandra nodes to be ran on a single host; somewhat (but nowhere near
> > entirely) similar to a pre-fork model used by some UNIX-based servers.
>
> I have pretty significant knee-jerk negative reactions to that idea to
> be honest, even if the pack is limited to a handful of instances. In
> order for vnodes to be useful with random placement, we'd need much
> more than a handful of vnodes per node (cassandra instances in a
> "pack" in that model).
>
> --
> / Peter Schuller (@scode, http://worldmodscode.wordpress.com)
>

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