In the last post we discussed about event based monitoring options SCOM provides with Monitors. You can find it here:
In this post we are going to discuss the event based monitoring options using SCOM Rules. Basically the highlighted options in the image below:
As we can see, we have 2 kinds of rules for monitoring events. “Alert Generating Rules” and “Collection Rules”. Let’s walk through them one by one.
Alert Generating Rules:
As the name suggests, this type of rules raise an alert if they detect the event ID.
As you’re going through the Rule Creation wizard you will notice that there are several options in “Rule category”, as shown in the pic below. In my experience, there is no difference whatever you choose. These are more like for “Logical Grouping” of these rules, that you can maybe make use of if working on them through Powershell. Since we’re here to create an “alert generating” rule, the most obvious option here would be “Alert”.
Now, this step is pretty important and if you’re new to creating this, you’re very likely to miss this. As you reach the final window, on the bottom of “Alert Description” (which you can modify btw), is the box for “Alert Suppression”. This is used to tell SCOM what events should be considered “duplicates” and hence not raise a new alert if there’s already one open in active alerts. “Auto-suppression” happens automatically for monitors – it only increases the repeat count for every new detection – but for rules, you’ll have to do this manually. If you don’t do this, you’re gonna get a new alert every time this event is detected. In this demo, I’m telling SCOM to consider the event as duplicate if it has the same Event ID AND the same Event Source.
I HIGHLY recommend using this since I learned this hard way some time back. I missed out configuring alert suppression for some rule and a couple nights later, woke up to a call from our Command Center guys. They said, “Dude! We’ve received THOUSANDS of emails in our mailbox since last 15 minutes…and they’re all the same. Help!”
I rushed and turned it off, further investigation brought to light the cause that something had gone wrong on the server and it was writing the same event over and over again, thousands of times in the event log, and since I had not configured the suppression criteria, it created a new alert every time and sent mail as set up in subscription. Now I check for suppression criteria at least 3 times 🙂
Now that is set up, I created the event in the logs with a simple PoSh:
Write-EventLog -Logname Application -ID 1000 -Source custom -Message "This is a test message"
And as you can see, the alert was raised.
Collection rules are used only to collect the events in the SCOM database. They do not create any alert. In fact, you’ll hardly even notice their presence at all. Why create these rules then? Most commonly for reporting/auditing purposes. You can also create a dashboard showing the detection of these events.
Notice in the left side of the wizard that there’s no “Configure Alerts” tab as we had in the “Alert Generating” rule.
So what this rule is going to do is detect the occurrence of event 500 with source “custom” and if it detects it, just saves it in the database.
I wrote this event in the logs a bunch of times, now let’s see if SCOM is really collecting them or not. We’ll create a simple “Event View” dashboard for this.
And yup, we can indeed see that the event is actually being collected by SCOM.
Here’s another thing that might be a bit tricky. After you create these 2 types of events, if you open the properties, you’ll see they’re almost identical. If you’ve named them properly, kudos to you but if you (or someone else) hasn’t, how will you find out whether the rule is generating alerts or just collecting events? Take a close look at the content in the yellow boxes below. See the difference?
Alert Generating Rule Properties:
Event Collection Rule Properties:
You rightly noticed that the response for the alert generating rule is “Alert”, which means this rule is going to respond to the event detection by generating an alert. If you click on the “Edit” option just beside that, you’ll see wizard for alert name change, format change, suppression criteria, etc.
On the other hand, the yellow box in the collection rule is “Event Data Collection Write Action” and “Event data publisher”, which indicates that it is only writing it in the databases. You can also verify this with Powershell:
You can also fetch a report for the event collection rule for auditing purposes, but unfortunately I do not have the Reporting feature installed in my lab so can’t show a demo for that. 🙂
Thus concluding the event monitoring options SCOM offers with monitors as well as Rules. Now you know what abilities SCOM has, now it’s up to you to decide which option do you wanna choose 🙂