sys.dm_os_wait_stats - This sysem related DMV will provide all the OS related information like,
1. Any I/O acitivity happening.
2. Context switching details
3. Pre-emptive switching.
4. Page / Extent related information.
5. Query waits
6. Memory usage
7. SQL Trace/backup/restore activities.
and Lot more. Try it, you will find a great usage of this DMV.
Cheers,