# Data Writing Process Review


![left](./student-guide/diagram/03-19-1.png)

------------------------------------------------------------

TiKV write data: The user's write request is submitted to the TiDB Server, which then sends the write request to the raftstore pool.raftstore pool converts the write request into a Raft log, and then stores the Raft log in rocksdb raft , and copied to another TiKV. Write request are written to rocksdb kv via apply pool after passing through the raftstore pool, and the data is written. The write process involves multiple components and networks in the graph, and can be divided into two categories. The first class is the thread pool class, which is related to the CPU. The second class is write and write IO related. You can first see if it's a thread problem or a write IO problem separately from the two main categories.