Every now and then I’ve seen questions regarding this on the Technet forums. The most usual question is “A service XXX failure alert is being generated by a server where this service isn’t even present! What’s going on?”
The Basic Service Monitor:
This is a simple monitor that simply puts an instance of the monitor you create on EVERY server where it’s targeted. Most of the times the class you select is “Windows Server”, and so the monitor is delivered to every Windows server – regardless of whether the service is actually present there or not.
I suggest you to create a brand new MP and save this monitor in it. Now, export it and analyze what you see in the XML. You’ll notice that there aren’t a lot of things, just a single simple monitor.
So what this basically does is to put up an instance of the monitor on EVERY instance of the target class. It does not bother to check whether the service actually even exists on that server or not. And this more often than sometimes causes false alerts stating that the service is “down” on the servers where it isn’t even present! This is why I call this the “dumb” service monitor.
If you want to apply this only on a group of servers, you need to go through the additional step of disabling this monitor and enable it through override explicitly for the group you’ve created.
Windows Service Template:
Now let’s create a service monitor using the Windows Service template. As you’ll notice while creating the monitor, this wizard offers much more than just simple service availability monitoring. You can also specify to get alerts based on how much CPU and memory the service is actually using.
While setting up the target for this monitor, you’d also notice that you need a group to target this against (instead of the whole classes as we did in case of basic service monitor). What this does is to provide the precise targeting for this monitor to where you want to run this. If you want to target this to all Windows servers in your environment, just select the “All Windows Computers” group.
Now, let’s do the same thing – save this in a separate test MP and export it for our analysis. You’ll see some interesting stuff in the XML.
This MP will be considerably larger than the previous one and the first thing you’ll notice is the discovery. This monitor creates it’s own discovery for the service. And when you have a discovery, you also have a class. As you create this monitor, SCOM automatically detects the presence of this service on the servers (in the group provided earlier) and populates the class. Once the class is populated, the monitoring is targeted only to the instances of this class, saving SCOM and you the trouble to narrow down the scope later. Pretty neat, eh? 🙂 This is why I like to call this the “intelligent” service monitor.
You’ll also see that when you create this one monitor, under the hood SCOM creates several monitors as well as rules:
|Monitors||Running state of the service||Enabled.|
|CPU utilization of the service||Enabled if CPU Usage monitoring is selected in the wizard.|
|Memory usage of the service||Enabled if Memory Usage monitoring is selected in the wizard.|
|Collection Rules||Collection of events indicating a change in service’s running states.||Enabled.|
|Collection of CPU utilization for the service||Enabled if CPU Usage monitoring is selected in the wizard.|
|Collection of memory usage for the service||Enabled if Memory Usage monitoring is selected in the wizard.|
|Collection of Handle Count for the service||Disabled. Can be enabled with an override.|
|Collection of Thread Count for the service||Disabled. Can be enabled with an override.|
|Collection of Working Set for the service||Disabled. Can be enabled with an override.|
So you see, this one wizard is actually creating THREE different monitors and SIX different performance collection rules. Also another upside of this is, since the class has also been created, you can target this class for any rules or monitors that you may want to create for this particular sub-set of servers where the service is running.
Another great thing about this is that since you have a class for this, you can even pull an availability report against this object to measure the uptime of your service.
OK then, which one should I choose?
After all said and seen, the obvious question you have in mind is probably one of the below:
- Cool, so the Windows Service template option looks pretty awesome. I should be using this one all the time, right?
- Wow, I never know that. I’ve never created a service monitor with the Windows Template option. Did I make a mistake?
- Why would anyone even create the basic service monitor then?
These are all legit questions, and you might be surprised to know my answer if you ask me my preferred way of monitoring a service. Yes, I (and many others) would still prefer the basic service monitor. Why? There are several reasons to do that.
- You only want to monitor the availability of the service. You are not concerned about the amount of CPU memory it is consuming. In fact, this is the case most of the times. You’re mainly focused only on the up/down status of the service. And in case you’re worried about CPU and memory utilization being consumed, you do have special dedicated monitors for them anyway.
- As the Window Service template creates a lot of things along with the service availability monitoring (1 class, 3 monitors and 6 rules), if you don’t actually need them, they’re just unnecessary overhead for SCOM. Now imagine you creating (1+3+6) 10 objects in SCOM for EACH service out of which 9 are not being used, how much litter you have created in SCOM. Basic service monitor on the other hand only creates 1 object (the actual availability monitor).
- It is much more work to disable the Windows Service template monitor than the basic service monitor. As you can imagine, if you no longer want to monitor the service, you’ll have to disable all 10 objects related to this monitor as opposed to just one in basic service monitor.
Hence, always first decide whether you REALLY want all this additional functionality that the Windows Service template provides, and if the answer is “Yes”, go for this way. Else, the good old basic service monitor is your friend 😉
Hopefully this clears up some things for you. 🙂