The fastest persistent key / value store out there

Pros

We were looking for speed and scalability, and with Aerospike we got exactly that. It's simple enough to manage, has some additional monitoring tooling. To avoid nasty surprising when buying this software - make sure you read the docs thoroughly, at least twice.

Cons

It's quite expensive. You have to use Aerospike's client libraries, which don't always offer compatibility with all the Aerospike features (mostly Ruby). Remote training sessions are very basic, you'll better off reading the documentation and asking support specific questions if anything's unclear.

Redis competitor, but not there yet

Pros

Operation per second was fastest among other in memory DB

Cons

It has no transactions -- the biggest flaw of this software, unless you are using it only for memory store it works great