A file-based data store is automatically created when you create a broker instance. The store is located in the broker’s instance directory; see Appendix A, Platform-Specific Locations of Message QueueTM Data for the exact location.
By default, Message Queue performs asynchronous write operations to disk. The operating system can buffer these operations for efficient performance. However, if an unexpected system failure should occur between write operations, messages could be lost. To improve reliability (at the cost of reduced performance), you can set the broker property imq.persist.file.sync to write data synchronously instead. For further discussion about this property, see File-Based Persistence and Table 14–5.
When you start a broker instance, you can use the imqbrokerd command’s -reset option to clear the file system store. For more information about this option and its suboptions, see Broker Utility.