Slow file copies and applications that pause while opening files can point to a storage bottleneck. Resource Monitor in Windows shows disk I/O performance by process and file, including transfer rates and response time.
The Processes with Disk Activity table identifies programs that are reading or writing. Selecting a process filters Disk Activity to its file activity, and the PID distinguishes programs that share an executable name. Windows can also attribute cached or background storage work to System.
Throughput and response time describe different aspects of disk performance. A high transfer rate can be normal during a copy, while a sustained rise in response time during a slowdown suggests requests are waiting longer. These live readings show current activity rather than disk health, and a virtual disk reflects the guest's view of storage.
Steps to monitor disk I/O in Windows:
- Open Resource Monitor from Windows Search.
- Select the Disk tab.
If the tables are cramped, the arrow above the graphs hides the graph pane, and dragging a column header's right border widens that column.
- Sort Processes with Disk Activity by Total (B/sec) with the largest values first.
The Total (B/sec) header toggles the sort direction. The Read (B/sec) and Write (B/sec) columns show bytes per second, and Total (B/sec) combines them.
- Select the checkbox beside the process whose disk activity you want to inspect.
- Expand Disk Activity if it is collapsed.
- Confirm that Disk Activity shows the selected PID with file paths, I/O rates, and Response Time (ms).
Response Time (ms) reports disk response time in milliseconds. Nonzero read or write rates show activity; an idle process can show zeros or no file rows. NTFS metadata such as C:\$LogFile can appear as part of an application's disk activity.