Active Directory (AD) can record sequential or circular logs. The default logging method is sequential. Sequential log files arenít overwritten with new data. These files grow until they reach a specified size. After all the transactions in a log file are committed to the database, the log file is unnecessary. ADís garbage-collection process deletes unnecessary log files every 12 hours by default. If your server doesnít stay up longer than 12 hours between reboots, AD canít clean up old log files. Eventually, the files will use all your available disk space.
Circular logs overwrite transactions at specific intervals. Some administrators prefer circular logging because this method helps minimize the amount of logged data the physical disk must store. To enable circular logging, you need to edit the Registry.