This counter counts direct I/O operations, transfers made straight into or out of a process's own buffer without going through the system's intermediate buffer cache. Applications doing their own buffering, such as database engines, typically rely heavily on direct I/O, so a high count here often reflects database or similarly I/O-intensive application activity. For example, a database server managing its own buffer pool and reading data files directly would drive this counter up noticeably during heavy transaction processing.