Message storage is the most complicated and important part of RocketMQ. This section will describe the three aspects of RocketMQ: message storage architecture, PageCache and memory mapping, and RocketMQ's two different disk flushing methods.
## 1. Message Storage Architecture
## 1 Message Storage Architecture
The message storage architecture diagram consists of 3 files related to message storage: `CommitLog` file, `ConsumeQueue` file, and `IndexFile`.
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@@ -33,4 +33,4 @@ In addition, RocketMQ mainly reads and writes files through `MappedByteBuffer`.
* synchronous flush: As shown above, the RocketMQ's Broker will return a successful `ACK` response to the Producer after the message is truly persisted to disk. Synchronous flushing is a good guarantee for the reliability of MQ messages, but it will have a big impact on performance. Generally, it is suitable for financial business applications.
* asynchronous flush: Asynchronous flushing can take full advantage of the PageCache of the OS, as long as the message is written to the PageCache, the successful `ACK` can be returned to the Producer. The message flushing is performed by the background asynchronous thread, which reduces the read and write delay and improves the performance and throughput of the MQ.
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* asynchronous flush: Asynchronous flushing can take full advantage of the PageCache of the OS, as long as the message is written to the PageCache, the successful `ACK` can be returned to the Producer. The message flushing is performed by the background asynchronous thread, which reduces the read and write delay and improves the performance and throughput of the MQ.
