After you set up the database for automatic expansion, when a database grows to its free space threshold, internal mechanisms fire, increasing the size of the database by the amount of space your expansion policies specify. The automatic expansion process measures the amount of room left on all devices bound to the database. If there is sufficient room on the devices, the database continues to grow. By default, if the size of the device is greater than 40MB, the size of the database is increased by 10 percent. If your datebase is smaller than 40MB, the size of the database is increased by 4MB. However, you can specify database resizing limits that match the needs of your site.

If any devices are configured for expansion, those devices expand next. Finally, the database is expanded on those devices.

This automatic expansion process runs as a background task and generates informational messages in the server’s error log about its progress.