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From Manu Zhang <owenzhang1...@gmail.com>
Subject Re: distribution of token ranges with virtual nodes
Date Wed, 09 Jan 2013 17:18:27 GMT
Is cassandra-shuffle command in the trunk? Or it is only included in the
Debian package? I don't find it in the trunk.


On Sat, Nov 3, 2012 at 2:18 AM, Eric Evans <eevans@acunu.com> wrote:

> On Fri, Nov 2, 2012 at 12:38 AM, Manu Zhang <owenzhang1990@gmail.com>
> wrote:
> >> It splits into a contiguous range, because truly upgrading to vnode
> >> functionality is another step.
> >
> > That confuses me. As I understand it, there is no point in having 256
> tokens
> > on same node if I don't commit the shuffle
>
> This isn't exactly true.  By-partition operations (think repair,
> streaming, etc) will be more reliable in the sense that if they fail
> and need to be restarted, there is less that is lost/needs redoing.
> Also, if all you did was migrate from 1-token-per-node to 256
> contiguous tokens per node, normal topology changes (bootstrapping new
> nodes, decommissioning old ones), would gradually work to redistribute
> the partitions.  And, from a topology perspective, splitting the one
> partition into many contiguous partition is a no-op; it's safe to do
> and there is no cost to speak of from a computational or IO
> perspective.
>
> On the other hand, shuffling requires moving tokens around the
> cluster.  If you completely randomize placement, it follows that you
> will need to relocate all of the clusters data, so it's quite costly.
> It's also precedent setting, and not thoroughly tested yet.
>
> --
> Eric Evans
> Acunu | http://www.acunu.com | @acunu
>

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