title: Cassandra is configured to lose 10 seconds of data by default?
body: <p>As the data in the Commitlog is flushed to the disk periodically after every 10 seconds by default (controlled by <code>commitlog_sync_period_in_ms</code>), so if all replicas crash within 10 seconds, will I lose all that data? Does it mean that, theoretically, a Cassandra Cluster can lose data?</p>