Hi, thanks for sharing this.

Can you examine which process is responsible for the disk usage?

Under NCrunch, most of the disk usage usually comes from the MSBuild/compiler calls, which run continuously in the background when source files are being changed. Unless you have tests that do a lot of I/O, tests likely won't cause this. The sliding build delay setting can reduce disk consumption from builds, though this may slow your response times down slightly. Note that MSBuild can include a broad range of tasks in addition to the complier .. if this has recently changed for you, there is the possibility that one of your toolsets has an MSBuild task that includes some very expensive I/O.

Can you check to see which files are being read/written when this goes crazy? (Under performance monitor, go to disk, choose the system process under the 'processes with disk activity' section, then watch the disk activity section).

My gut feel here is that there is something with deep access in the system (i.e. probably not NCrunch) that is triggering in response to NCrunch's activity. Perhaps a virus scanner or some device driver.