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How to monitor a VMware ESXi 5 / 6 host with Check_MK & OMD

Recently I posted a guide detailing how to install OMD (Open Monitoring Distribution) on Ubuntu 14.04. Part of OMD is the Check_MK network monitoring platform. I consider it the best available in the Open Source world. Check_MK supports monitoring VMware ESXi hosts, as well as vSphere servers. It uses the vSphere API to communicate with the host, so it’s able to pull much more data than SNMP. It’s not exactly a very intuitive process to get an ESXi host added to Check_MK, but it’s very easy if you know what to do. The documentation available is sub par, at best. So, I’m going to change that! This guide applies to all versions of ESXi 5 or later. So, ESXi 5, 5.1, 5.5 and 6.

Check_MK is capable of monitoring all sorts of valuable data from an ESXi host. This includes, CPU usage, RAM usage, Datastore usage, Network bandwidth statistics, health sensors and virtual machine power state.

How to add an ESXi 5, 5.1, 5.5 or 6 host to Check MK

Go ahead and log in to your Check_MK web interface. In the Configuration navigation area of the left, click on Host & Service Parameters.

Screen Shot 2015-05-26 at 3.23.21 PM

Once you are here, select “Datasource Programs.”

Screen Shot 2015-05-26 at 3.24.42 PM

Select the line that says “Check state of VMWare ESX vis vSphere.”

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You can create the rule in the Main directory, or somewhere else if you like. It doesn’t matter.

Screen Shot 2015-05-26 at 3.26.22 PM

There are three settings you need to be concerned with here.

  • Specify explicit host names
  • vSphere User name
  • vSphere secre

You should create a read-only account in ESXi / vSphere in a production environment. You can enter an FQDN, hostname, or IP in the hosts field.

Screen Shot 2015-05-26 at 3.27.44 PM

Click Save.

At the top, go ahead and click on “1 Change” and then “Activate Changes!

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Now, select “Hosts” in the configuration navigation menu on the left.

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Select “Create new host.”

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The only thing you need to do here is enter the FQDN, Hostname, or IP Address of the ESXi Host / vSphere server in the Hostname field.

Screen Shot 2015-05-26 at 3.33.11 PM

Now, click on “Save & go to Services.”

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All available sensors will be checked by default, and unless you don’t want specific items to be monitored, go ahead and click on “Save manual check configuration.”

Screen Shot 2015-05-26 at 3.36.07 PM

Now, click on “2 Changes” at the top, and then “Activate Changes!

Screen Shot 2015-05-26 at 3.36.25 PM

All done! You can click on “Hosts” under views and your ESXi host will now be listed. It will take about 3-5 minutes for it to pull all of the initial sensor data. Once is does you will be monitoring CPU, RAM, Datastores, Network Cards, Virtual Machine power state, and much much more!

Screen Shot 2015-05-26 at 3.40.48 PM

If you run into any problems, feel free to ask for help in the comments below. Thanks!

5 thoughts on “How to monitor a VMware ESXi 5 / 6 host with Check_MK & OMD

  1. Mark says:

    How do you monitor if physical nics (vmnics) are down on the ESXi host?

  2. Besse says:

    Does someone know how I can get the state of a specific process on an ESX, we installed Xorg on it and we want to know if it runs or no.
    Frédéric Besse

  3. Lukas says:

    I have an issue in VMware vSphere Events & Tasks.
    I check the ESX Hosts every 10 minutes. Each time the check runs, the read-only user “Monitoring” loggin in to the esx Hosts to get the latest informations.
    VMware creates at least one Event in the Event log, f. i. User logged in, User logged out (at VMware vSphere Client).
    This floods the Event log with this wasteful Information.
    Is it possible to disable the collection of user Logins in the Event log?
    Thank you.

    • Mike Smith says:

      That’s a good question. I don’t know off the top of my head, but let me take a look at one of my lab servers and see if I can come up with something.


  4. Ertekin says:

    we have check_mk inside of OMD. We add all Hosts (vSphere 6.0) to check:mk. We have at all Hosts the Warnin:”WARN – unexpected agent version 6.0 (should be 1.2.6p12), execution time 1.1 sec”. How can i fix this Problem?


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