DaveWentzel.com All Things Data
Introduction to DMV's
In SQL 2005 MS has opened the blackbox to let you see the rich data that is under the covers that is critical to server performance. This allows you to have a more transparent server. This gives you the ability to roll your own (or find/buy your own) monitoring tool. The DMVs are just the plumbing for something that can be designed to look under the covers. An example tool is the dashboard reports that you can download from MS and run from SSMS.
But you have to know and understand the DMVs to unleash their power. Here I hope to accomplish some of that.
DMVs and DMFs exist in the Resource db and are made available in the sys schema.
DMV data is "reset" whenever SQL Server restarts. So, you need to keep this in mind when you are looking at the stats. If the instance was just restarted you may not see very useful information. On the flip side, if you instance has been running for a long period of time you can assume that the older stats might have been "aged" out on some of views.