The SQL Server Database Engine automatically executes the CHECKPOINT command to write all dirty pages from the Buffer Cache of the current database to disk. Dirty pages are the data pages which were stored in the Buffer Cache and were modified, however they have not yet been written to disk. This process helps the SQL Server Database Engine save time during database recovery in the event of a sudden system crash or an unexpected SQL Server shutdown.
Checkpoint [ checkpoint_duration ]
When checkpoint_duration is specified, the SQL Server Database Engine attempts to perform the checkpoint within the requested duration. The checkpoint_duration must be an expression of type int, and must be greater than zero. When this parameter is omitted, SQL Server Database Engine automatically adjusts the checkpoint duration to minimize the performance impact on database applications.