Re: Cassandra Cluster Expansion Criteria

[Jeff Jirsa]

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  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  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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Re: Cassandra Cluster Expansion Criteria

[Anuj Wadehra]

Hi Asad,
First, you need to understand the factors impacting cluster capacity. Some of 
the important factors to be considered while doing capacity planning of 
Cassandra are:
1.  Compaction strategy: It impacts disk space requirements and IO/CPU/memory 
overhead for compactions.
2. Replication Factor: Impacts disk space.
3. Business SLAs and Data Access patterns (read/write)
4. Type of storage: SSD will ensure that IO is rarely a problem. You may become 
CPU bound first.
Some trigger points for expanding your cluster:
1. Disk crunch. Unable to meet free disk requirements for various compaction 
strategies.
2. Overloaded nodes: tpstats/logs show  frequent dropped mutations. 
Consistently high CPU load.
3. Business SLAs not being met due to increase in reads/writes per second.
Please note that this is not an exhaustive list.
ThanksAnuj







Sent from Yahoo Mail on Android 
 
  On Thu, Jun 29, 2017 at 7:15 PM, ZAIDI, ASAD A 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
 
  
 
  
 
  
 
  
   

Re: Cassandra Cluster Expansion Criteria

[Nitan Kainth]

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  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

Cassandra Cluster Expansion Criteria

[ZAIDI, ASAD A]

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