Cassandra Commit Log is an append only log that is used to track the mutations made to Column Families and provide durability for those mutations. Every mutation is appended to a Commit Log first before applied to an in memory write-back cache called Memtable. If a Memtable is not flushed to disk to create a SSTable then the mutations stored in it can be lost if Cassandra suddenly shutdowns or crashes. At startup, Cassandra replays the Commit Log to recover the data that was not stored to dis...
