Monitoring Windows servers – with SNMP

UPDATE: Did you knew there’s an official Cacti guide? Find it at Cacti 0.8 Beginner’s Guide. For more info about SNMP please don’t hesitate to take a look at Essential SNMP, Second Edition.

My previous article was focused on Linux monitoring. Often, you’ll have in your datacenter at least a few Windows machines. SQL Server is one of the best excuses these days to get a Microsoft machine in your server room – and you know what, it’s a decent database – well, at least for medium-sized companies like the one I’m working for right now.

It is less known, but yes you can have SNMP support out of the box with Windows 2000 and XP, and it doesn’t need to be the Server flavor

1. Invoke the Control Panel. 2. Double click the Add/Remove Programs icon. 3. Select Add/Remove Windows Components. The Windows Component Wizard is displayed. 4. Check the Management and Monitoring Tools box. 5. Click the Details button. 6. Check the Simple Network Management Protocol box and click OK, then Next. You may have to reboot the machine.

After the server is installed, the SNMP service has to be configured. Here’s how:

1. Invoke the Control Panel. 2. Double click the Administrative Tools icon. 3. Double click the Services icon. 4. Select SNMP Service. 5. Choose the Security tab. 6. Add whatever community name is used in your network. Chances are in a local internal LAN the default public works out of the box. 7. For a sensitive server, you may want to fiddle a little bit with the IP restriction settings, for instance allowing SNMP communication only with the monitoring machine. 8. Click OK then restart the service.

Next step is Cacti integration. Unfortunately, there is no Windows-specific profile for devices in Cacti. Therefore if you have lots of Windows machines, you’ll have to define your own. Or, take a Generic SNMP-enabled host and use it as a scaffold for each device configuration.

Out of the graphs and datasources already defined in Cacti [I am using 0.8.6c] only two work with Windows SNMP agents: processes and interface traffic values.

It’s a good start, but if you are serious about monitoring, you need to dig a little bit deeper. Once again, the MIB Browser comes to save the day. It’s very simple, just search on the Windows machine for any .mib files you are able to find, copy on your workstation, load them into the MIB browser and make some recursive walks (Get subtree on the root of the MIB).This way, I was able to find some interesting OID for the Windows machine. For instance, .1.3.6.1.2.1.25.3.3.1.2.1 -> .1.3.6.1.2.1.25.3.3.1.2.4 the OID for CPU load on each of the 4 virtual CPUs [it’s a dual Xeon with HT].

Memory-related OIDs for my configuration are :

- .1.3.6.1.2.1.25.2.3.1.5.6 – Total physical memory - .1.3.6.1.2.1.25.2.3.1.6.6 – Used physical memory - .1.3.6.1.2.1.25.2.3.1.6.6 – Total virtual memory [“virtual”=”swap” in Windows lingo] - .1.3.6.1.2.1.25.2.3.1.6.6 – Used virtual memory

Here’s a neat memory chart for a windows machine. Notice that the values are in “blocks” which in my case is 64kb. The total physical memory is 4GB.

Most hardware manufacturers do offer SNMP agents for their hardware, as well as the corresponding .mib file . In my case, I was able to install an agent to monitor an LSI Megaraid controller. Here is a chart for the number of disk operations/second:

In one of my next articles, we’ll take a look together at the way you can export “non-standard” data over SNMP from Windows, in the same manner we did on Linux, using custom scripts. Till then, have an excellent week.

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