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From Sebastian Estevez <>
Subject Re: Do vnodes need more memory?
Date Wed, 23 Sep 2015 14:14:31 GMT
This is interesting, where are you seeing that you're collecting 50% of the
time? Is your the default? How much ram?

Also, can you run this tool and send a minute worth of thread info:

java -jar sjk-plus-0.3.6.jar ttop -s localhost:7199 -n 30 -o CPU
On Sep 23, 2015 7:09 AM, "Tom van den Berge" <>

> I have two data centers, each with the same number of nodes, same hardware
> (CPUs, memory), Cassandra version (2.1.6), replication factory, etc. The
> only difference it that one data center uses vnodes, and the other doesn't.
> The non-vnode DC works fine (and has been for a long time) under
> production load: I'm seeing normal CPU and IO load and garbage collection
> figures. But the vnode DC is struggling very hard under the same load. It
> has been set up recently. The CPU load is very high, due to excessive
> garbage collection (>50% of the time is spent collecting).
> So it seems that Cassandra simply doesn't have enough memory. I'm trying
> to understand if this can be caused by the use of vnodes? Is there an
> sensible reason why vnodes would consume more memory than regular nodes? Or
> does any of you have the same experience? If not, I might be barking up the
> wrong tree here, and I would love to know it before upgrading my servers
> with more memory.
> Thanks,
> Tom

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