When we first started to think about developing a power management solution specifically for servers, we had to first decide if there was a good reason to do so! When we developed NightWatchman for PCs, it was reasonably clear that there was (and still is) huge demand and opportunity for cost savings by implementing sensible and safe power management. After all there are millions of desktops out there, and the ratio of servers to PCs is at least 10 to 1, so the numbers are there, but what about the approach?

PC Power Management

With PC Power Management it is easy to categorize large groups of PCs and the working requirements of their users. A PC is either: on -  for the user, on -  for maintenance or off - because it is not required for either of the two previous requirements. Of course you can be a little more sophisticated in terms for monitor standby when the user is temporarily away from the PC etc but these are the main opportunities to save energy.

Server Power Management

Servers exist for very different reasons to PCs. A server exists to provide a service to someone or something.  The type of service, and the availability required for those services is almost limitless. What is quite fundamental however is the following.

If a server isn't providing the service it's supposed to, to the users (or devices) that require it then it should not be consuming power.

Of course a server that is not providing a useful service is not only consuming energy. It still requires backup, maintenance, upgrade and also contributes to the cooling requirements of the data center.

Anyway, that is the basic premise for NightWatchman Server Edition. It also became clear that you need to treat each server on an individual basis. So, to categorize the various states of servers we can use the following. These various states are graded in terms of energy efficiency, with A being the highest grade.

Grade A = Off.
Grade B = On and using most of its resources to do what it is supposed to be doing.
Grade C = On but using very little of its resources to do what it is supposed to be doing.
Grade D = On but using very little of its resources to do anything other than what it is supposed to be doing.
Grade E = On but using most of its resources to do anything other than what it is supposed to be doing.

So, the goal of NightWatchman Server Edition is to ensure that you run the minimum number of servers at the highest grade possible. Simple huh?

Here's a real world example of how we could use the above criteria.

Consider  the following two servers:
Server One
A branch office file server with no remote access. Office hours are 9am till 6pm so there is no possibility of anyone requiring these services outside of those hours.
Recommendation: Save power by turning the server off after office hours

Server Two
A door entry system requires access to a database to confirm your smart ID badge permits access. Access to offices outside of working hours is restricted, but the rest of the building remains open 24 hours a day. Turning this server off is not an option at any time. However, the door entry software consumes few resources so could be hosted on the branch file server.
Recommendation: Save power by consolidating onto Server One and decommissioning Server Two.

The complication is that acting on Server Two changes the recommendation for Server One demonstrating that Server Power Management is an ongoing task, not a one off piece of analysis. As your environment changes, the ideal power management policies will change too.

So you can see that Server Power Management is a complex task. Defining the policies that enable you to save energy and cost would be an enormous project if it were undertaken manually. It would take months to even get to a point where you could start to make some changes, and by that time it is quite possible that your results would be out of date! Such is the complex and fast moving environment that we inhabit today.

NightWatchman Server Edition provides you with the reporting and power management tools to automate the above process, and in doing so ensures that all your servers are working in the most energy and cost efficient way possible. In forthcoming blog posts - we'll show you just how it's done!

Read the complete post at http://www.1e.com/bizblog/post/2009/11/02/Why-Server-Power-Management.aspx