Cassandra is still in its early stages in many ways, not yet seeing its 1.0 release at the time of this writing. There are few easy, graphical tools to help manage it, and the community has not settled on certain key internal and external design questions that have been revisited. But what does it say about the promise, usefulness, and stability of a data store that even in its early stages is being used in production by many large, well-known companies?
The list of companies using Cassandra is growing. These companies include:
Cassandra is also being used by Cisco and Platform64, and is starting to see use at Comcast and bee.tv for personalized television streaming to the Web and to mobile devices. There are others. The bottom line is that the uses are real. A wide variety of companies are finding use cases for Cassandra and seeing success with it. As of this writing, the largest known Cassandra installation is at Facebook, where they have more than 150TB of data on more than 100 machines. Many more companies are currently evaluating Cassandra for production use in different projects, and a services company called Riptano, cofounded by Jonathan Ellis, the Apache Project Chair for Cassandra, was started in April of 2010. As more features are added and better tooling and support options are rolled out, anticipate even broader adoption.