James Hamilton has published a thorough summary of Facebook's Cassandra, another scalable key-value store for your perusal. It's open source and is described as a "BigTable data model running on a Dynamo-like infrastructure." Cassandra is used in Facebook as an email search system containing 25TB and over 100m mailboxes. # Google Code for Cassandra - A Structured Storage System on a P2P Network # SIGMOD 2008 Presentation. # Video Presentation at Facebook # Facebook Engineering Blog for Cassandra # Anti-RDBMS: A list of distributed key-value stores # Facebook Cassandra Architecture and Design by James Hamilton