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List:       cassandra-dev
Subject:    Re: What would be the appropriate number of vnodes (num_tokens) to use?
From:       kurt greaves <kurt () instaclustr ! com>
Date:       2017-10-10 1:42:44
Message-ID: CAPbVhuNRNSzxptLuq0vShYFZGQjSeTpSyDLvksMjugP+TKxuVg () mail ! gmail ! com
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>
> If you had more vnodes per
> machine, you could stream more ranges in parallel, taking advantage of more
> cores, streaming significantly faster. This is a very real gain if you are
> regularly adding or removing a FEW nodes.

In our experience 16 vnodes for streaming is much like 256. You tend to hit
other streaming bottlenecks in Cassandra pretty quickly, and 16 vnodes is
generally enough to give the streaming benefit (which isn't really that
much in practice).
I'd still say for any cluster over 20 nodes single tokens are the way to
go, despite the reduced streaming performance, but if you really don't want
to manage tokens certainly aim for 16 - 64 (depending on topology 16 may
not work that well until you get to 30ish nodes or more).
​


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