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From "Jeff Jirsa"<jji...@apache.org>
Subject Re: Cassandra Cluster Expansion Criteria
Date Thu, 29 Jun 2017 20:43:04 GMT

50% disk free is really only required with STCS (in size tiered compaction, if you have 4
files of a similar size, they'll be joined together - there are theoretically times when all
of your data is in 4 files of the same size, and to join them together you'll temporarily
double your disk space). With LCS (and TWCS), you should be able to go to 70% or so, most
of the time, because that "join everything together" compaction never happens in those strategies.

Keep an eye on CPU load and latencies - if you see it trending in the wrong direction beyond
what you can tolerate in your SLA, you may want to consider scaling.


On 2017-06-29 06:48 (-0700), Nitan Kainth <nitan@bamlabs.com> wrote: 
> Ideally you should maintain 50% disk space.
> SLA and Node load is also very important to make the decision.
> 
> > On Jun 29, 2017, at 6:45 AM, ZAIDI, ASAD A <az192g@att.com> wrote:
> > 
> > Hello Folks,
> >  
> > I’m on Cassandra 2.2.8 cluster with 14 nodes , each with around 2TB of data
volume. I’m looking for a criteria /or data points that can help me decide when or  if
I should add more nodes to the cluster and by how many nodes.
> >  
> > I’ll really appreciate if you guys can share your insights.
> >  
> > Thanks/Asad
> 
> 

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