The data in IoTDB is divided into three categories, namely data files, system files, and pre-write log files.

Data files store all the data that the user wrote to IoTDB, which contains TsFile and other files. TsFile storage directory can be configured with the configuration item (see for details). Other files can be configured through data_dirs configuration item (see for details).

System files include schema files, which store metadata information of data in IoTDB. It can be configured through the configuration item (see System Layer for details).

Pre-write log files store WAL files. It can be configured through the configuration item (see for details).

The data directory path included in storage directory setting are: base_dir, data_dirs, multi_dir_strategy, and wal_dir, which refer to system files, data folders, storage strategy, and pre-write log files.

An example of the configuration items are as follows:

• Save all system files in $IOTDB_HOME/data
• Save WAL data in $IOTDB_HOME/data/wal