When SQL Server has no user tasks to process, a housekeeper task automatically begins writing dirty buffers from cache to disk. Because these writes are done during the server’s idle cycles, they are known as free writes.
The benefits of the housekeeper task are:
Improved CPU utilization
Decreased need for buffer washing during transaction processing
Faster checkpoints
Shorter recovery time
In applications that repeatedly update the same database page, the housekeeper task may initiate some database writes unnecessarily. System Administrators can use the housekeeper free write percentage configuration parameter to disable the housekeeper task or to control its side effects.
For more information about the housekeeper task, see Chapter 21, “How Adaptive Server Uses Engines and CPUs,” in the Performance and Tuning Guide.
