MOM 2005: Computer Groups and Computer Rules what’s the deal?

Since I started at Microsoft as a Premier Field Engineer I went to quite some customers still using MOM 2005, so for all of you already working with OpsMgr 2007 (SP1) here some "old school" info on Computer Groups and Computer Rules in MOM 2005.

What are Computer Groups?
Computer Groups allow you to group together similar computers so that you can assign rules to group or computer and not individually to each computer.

Features of Computer Groups:

  • Are created based on computer attributes.
  • Can have rules associated with them.
  • Can be nested.
  • Are organized into a logical structure.
  • Support static and dynamic membership.

Are used for:

  • Applying event, alert, or performance rules.
  • Calculating the state of the computer group.
  • Creating console scopes for the operators.
  • Viewing Computers.

By default, the MOM server scans the network for all managed computers every 24 hours to detect changes or modifications in the network. During the scan process, the MOM server accesses the Active Directory service for the names of the computers, read certain registry keys or values, and identifies the type of computer. Then it places the computers in the appropriate computer groups and finally includes or excludes the computer.

What are Rule Groups?
Rules help you specify the events, performances, and alerts that need to be monitored on the managed computers. Rules also enable you to set the actions that are to be taken in response to the monitored events, performances, and alerts.

Features of Rule Groups:

  • Help organize the rules based on the application that needs to be monitored.
  • Enable you to associated a computer group with a group of rules.
  • Can contain event, alert,or performance rules.

Are used for:

  • Specify the performance data to be collected from managed computers.
  • Determine how the collected data should be processed.
  • Filter irrelevant data.
  • Specify the responses to be generated for events and alerts.

For ease of administration, you can group several rules to form a rule group. A rule group is a named set of processing rules that allows administrators to easily associate many processing rules with a computer group. Rule groups are provided by Management Packs, but you can also create your own.

All this got me triggered by a question of a customer about the Microsoft SQL Server 2005 Service Discovery Computer Group. Have you ever take a look at that Computer Group? No? Follow me...


If we look at the Formula for the computer group (AttributeValue(Microsoft Windows Current Version)>="5.0") this means that all computers with an Operating System of Windows server 2000 and higher are members of this computer group. Why would you create this Computer Group? This is because Computer Groups are used to group together similar computers so that you can assign rules to group or computer and not individually to each computer.

Ok, now this is clear we have to find which Rule Groups are associated to this Computer Group. And guess what? It's the SQL Server 2005 Detection and Group Membership Rule Group.


That Rule Group only contains one Rule SQL Server Detection and Group Membership, which runs every 30 mins a script to discover installed instances of SQL Server and Reporting Services and add them to Discovered Groups. But why is this rule running on all Windows server 2000 and higher computers and not only running on computers running SQL, you might ask? This is due the fact that the MP could never detect SQL on 64 bit machines and you used to have to do work rounds by manually adding the server to computer groups.

Have fun learn MOM and OpsMgr!

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