How does the Cassandra Timeline ensure data durability?

The correct choice emphasizes the importance of structured log writes to the Commit Log in ensuring data durability within Cassandra. The Commit Log is a critical component that records every write operation. When a write occurs, Cassandra first logs the details of the write to the Commit Log before persisting the data to the memtable or sstable. This mechanism ensures that even if a failure occurs shortly after a write, the data can be recovered from the Commit Log, maintaining data integrity and durability.

Moreover, the structure of the Commit Log allows for efficient and reliable data writes. By using this approach, Cassandra can guarantee that data is not lost in the event of unexpected crashes or power failures, reinforcing the durability aspect of the database system.

Other methods such as data compression, data replication, and system updates play significant roles in performance, availability, and management but do not directly relate to the specific mechanisms that ensure data durability in the same way that the Commit Log does.