Cassandra is in wide use around the world, and usage is growing all the time. Companies like Netflix, eBay, Twitter, Reddit, and Ooyala all use Cassandra to power pieces of their architecture, and it is critical to the day-to-da operations of those organizations. to date, the largest publicly known Cassandra cluster by machine count has over 300TB of data spanning 400 machines.
Because of Cassandra's ability to handle high-volume data, it works well for a myriad of applications. This means that it's well suited to handling projects from the high-speed world of advertising technology in real time to the high-volume world of big-data analytics and everything in between. It is important to know your use case before moving forward to ensure things like proper deployment and good schema design.
