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 <jagernico...@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 >
