[MalcolmDiggs]

Until recently I was running a 500GB cluster (500 million records of about 1kb each) and it cost me almost a grand a month. But, most of these costs were from the provisioned throughput capacity, not the storage.

I never had any scaling problems, availability problems, data corruption or anything like that. It did exactly what it claimed to do.

Remember that Dynamo is a database as a service (it's not something you have the option of running on your own servers). So it's not comparable to MongoDB exactly, it's more like a hosted MongoDB service. For me, a comparable MongoDB cluster hosted at compose.io would have cost me 6 grand a month, MongoLab would have cost me about 3 grand a month, so the pricing felt ok.

That being said, don't expect MongoDB features, Dynamo is setup more like a simple key-value store (although you could force it to store documents, you won't get the indexing/searching/filtering capabilities of mongo).

If you want fault-tolerance and practically unlimited scalability it's a good choice. Just as long as you don't need to get tons of data in and out all time (that's when the provisioned throughput costs go soaring). It's also a complete pain in the ass to export data (it's a whole pipeline-to-mapreduce-to-hive thing).