Cassandra 1.0 introduces support for data compression on a per-ColumnFamily basis, which maximizes storage capacity by reducing data volume on disk. Compression also reduces disk I/O and improves both read and write performance. It is best suited for ColumnFamilies with many rows having the same columns or many columns in common. Enabling compression can be done during column family creation or update, and existing SSTables are compressed during normal Cassandra compaction process.