I am using MongoDB and it works like I want it but I am roasted all the time on HN because of it and told to be using Redis instead. Still considering the switch but I don't want to run into problems like this.
Redis is usually used for caching and scaling that DB's have a hard[er] time with. Not as a primary datastore.
Also MongoDB and Redis have very few overlapping use cases, they're not really comparable.
From what I've been told MongoDB breaks in really bad and silent ways when under pressure. And I mean "ignore writes without giving out errors" kind of bad.
Because none of what you said is really all that true. MongoDB has never ignored writes without giving errors. You have always been able to check if the write failed. The issue I think you're referring to is the F_SYNC immediately to disk default. Which was changed many years ago and was never the default for any of the language clients.
MongoDB is a great database in specific situations.
And you may be right about that configuration, but I cannot remember the exact details of the discussion.
Either way, don't get me wrong. I use MongoDB as well, and am quite fond of its aggregation framework. It's just not something that I catalog as "reliable and high performance" the way I do redis (which of course, also has limitations of its own).