No the i in icache is not for ignite, it is for item. This is really just a historical anecdotal reason more than anything (There's 2 hard problems in computer science: Naming things, Cache Invalidation, and off-by-one errors). In the original implementation of persistence so-called "items" were the only thing that were stored (weapons, armor, power plants, etc..), so ecache for entity cache may have beeen more prescient, but icache has stuck and so it goes.

Now to answer your question, will it sit on top of open source? Yes and no. First I'll be a bit more particular and point out that technically the icache service fleet is one part of a larger ecosystem of services and gameside systems for the full global persistence and server streaming architecture. So if we are to just talk about icache itself, then largely it is a custom written solution. That said the backend team does use some open source libraries so it isn't entirely proprietary, but it is definitely not Ignite from Apache. However if you pull back further and look at the wider ecosystem you can definitely find tech that is built on open source technology such as Kafka, Redis, Mongodb, etc... and we are also looking to move parts of our backend to a cloud native architecture including the use of grpc. There's a ton of work that has gone into these projects and where they make sense we will definitely leverage them, though there will always be times that the best solution will be something we will need to make ourselves for a project as unique as Star Citizen.