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From Léo FERLIN SUTTON <lfer...@mailjet.com.INVALID>
Subject Re: Sizing a cluster
Date Tue, 01 Oct 2019 12:57:58 GMT
Hi !

I'm not an expert but don't forget that cassandra needs space to do it's
compactions.

Take a look at the worst case scenarios from this datastax grid :
https://docs.datastax.com/en/dse-planning/doc/planning/capacityPlanning.html#capacityPlanning__disk

> The size of a picture + data is about 0.5MB

Is that the size of the uncompressed data or the data once it has been
inserted and compressed by cassandra ?
Looking at the cassandra compression :
http://cassandra.apache.org/doc/latest/operating/compression.html and
testing different parameters on a test cluster might be interesting before
you do the sizing of the final production cluster,

Regards,

Leo

On Tue, Oct 1, 2019 at 1:40 PM <jagernicolas@legtux.org> wrote:

> Hi,
> We want to use Cassandra to store camera detection. The size of a picture
> + data is about 0.5MB. We starting with 5 devices, but we targeting 50
> device for the next year, and could go up to 1000. I summary everything ,
>
>    - Number of sources: 5 - 50 - 1000 (src)
>    - Frequency of data: 1Hz (f)
>    - Estimate size of data: 0.5MB (s)
>    - Replication factor: 3 (RF)
>
>
> I calculated the size per year,
>
>    - src * f *60 * 60 * 24 * 365 * s
>
>
> gives me,
>
>    - 5 sources = 0.24 PB per year
>    - 50 sources = 2.4 PB per year
>    - 1000 sources = 47.3 per year
>
>
> so if respect the 2TB rule, I got, 120 nodes in the simplest case (5
> sources). Am I right ?
>
> regards,
> Nicolas Jäger
>

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