Dynamic Management Views and Dynamic Management Functions - Microsoft SQL Server 2012 Performance Tuning - page 172

The I/O statistics provided by sys.dm_io_virtual_file_stats() function and sys.
dm_io_pending_io_requests are very useful in troubleshooting the issues with disk
subsystem. You can monitor I/O operations being performed on files by looking at their
usage statistics. You can easily find out database files having high degree of disk usage,
with frequent resource-intensive read/write operations being performed on them, degrading
the disk I/O throughput and thus causing I/O bottlenecks. Once you identify the files and
databases responsible for the degradation of the I/O performance, you can either investigate
the root cause of such a high degree of I/O operations or move those databases/files to
different physical disks.