Kwa ndani, Kafka huhifadhi data kama append-only log kwenye disk (iliyopangwa katika segments), hutumia mbinu za I/O zenye ufanisi, na husimamia metadata ya cluster kupitia ZooKeeper (kihistoria) au KRaft (sasa). Kuelewa internals kunaongeza uelewa wa tabia na performance ya Kafka.
Commit log storage
Each partition is an append-only LOG stored on disk, split into SEGMENTS (files):
→ new events are APPENDED to the end (sequential writes → fast)
→ events are immutable once written; identified by OFFSET
→ old segments are deleted (retention) or compacted
→ an INDEX maps offsets to file positions (fast lookups)
→ the append-only log is the core of Kafka's design (durable, sequential, efficient)
