I'm sure this will result in a deep pit of flames, and I did try a search first, but can someone explain what purpose of service groups is really? I have been using Nagios about a year and I'm looking to reorganize the configuration better. Our servers are a mix between SQL boxes and Web servers. All our servers need to have the same basic checks, ping CPU, memory usage, and disk usage (on C:). The web servers get a few extras for HTTP, some custom services, and indexing.
I understand that a host group is a group of hosts, and a service group is a group of services. What seems to be confusing me is when you would define a service group and why. Would I simply lump say, indexing service, HTTP, and our proprietary service into a group, and then apply that group to the servers? It seems a little weird to list out the host with the service in the group. It seems to be the same thing to list out the hosts to be monitored in the service itself, or put the host group in the service itself.
What am I missing?