How many keyspaces can you reasonably have? We have around 500 customers and expect that to double end of year. We're looking into C* and wondering if it makes sense for a separate KS per customer?

If we have 1000 customers, so one KS per customer is 1000 keyspaces. Is that something C* can handle efficiently? Each customer has about 10 GB of data (not taking replication into account).

Or is this symptomatic of a bad design?

I guess the same question applies to our notion of breaking up the column families into time ranges. We're naively trying to avoid having few large CFs/KSs. Is/should that be a concern?

What are the tradeoffs of a smaller number of heavyweight KS/CFs vs. manually sharding the data into more granular KSs/CFs?

Thanks for any info.