I recently encountered an interesting question, maybe not the one you will see every day. A vCenter Center server runs a large number of Clusters; the VMs on those clusters are controlled by a considerable number of DRS rules. The question that raised; “How do we know if the DRS rules we once designed are still in place?” In the course of time, rules can be disabled, VM or Host groups does not match any more. Trying to answer this question by going through the vCenter Server configuration is not the way to go.
Thankfully, the VMware PowerCLI contains a useful Cmdlet Get-DrsRule that enables you to create a dump of the configured rules for each cluster. This makes checking your configuration a lot easier.
But there is another thing, now we know about the configuration, but what do we know about the actual situation? For instance, VM to Host affinity has “should” and “must” rules, but to what extent is a “should” rule fulfilled?
So time to create a PowerShell script which performs the following tasks; for each Cluster within a vCenter Server, a dump of the configured DRS rule is made. The second part of the script determines on which host a VM is running and compares it to the configured rules. The script will also report if a DRS rule is disabled and displays the power state of each VM. You will probably worry less about a powered down VM.
The script can be found here on GitHub.
I am aware that the script and my programming skills are far from perfect, so expect updated versions in the future.
- Install and configure vSphere PowerCLI
- Install and configure Update Manager PowerShell Library
- Use basic and advanced Cmdlets to manage VMs and ESXi Hosts
- Use Web Service Access Cmdlets
- Use Datastore and Inventory Providers
- Given a sample script, modify the script to perform a given action
Install and configure vSphere PowerCLI
vSphere Power CLI User’s Guide 5.0, Chapter 3 “Installing vSphere PowerCLI”, page 15.
vSphere Power CLI User’s Guide 5.0, Chapter 2 “vSphere PowerCLI System Requirements” presents an overview of the supported Operating Systems, required software and supported VMware environments.
Windows versions starting from XP SP2 are supported. To run vSphere PowerCLI, you need:
- .NET 2.0 SP1
- Windows PowerShell 1.0/2.0
Most VMware environments are supported.
vSphere PowerCLI can be downloaded from: http://www.vmware.com/go/powercli
Installation is straightforward. If the PowerShell Execution Policy on your machine is set incorrectly, a warning message appears before finalizing the vSphere PowerCLI installation. Ignore it and continue with the installation.
For security reasons, Windows PowerShell supports an execution policy feature. It determines whether scripts are allowed to run and whether they must be digitally signed. By default, the execution policy is set to Restricted, which is the most secure policy. If you want to run scripts or load configuration files, you can change the execution policy by using the Set-ExecutionPolicy cmdlet.
Start the vSPhere PowerCLI console and type:
Recently, Trainsignal presented a new episode in its VMware Training Videos series entitled “VMware vSphere PowerCLI Training”. The training is presented by Mr. Hal Rottenberg, a well known member in the PowerShell and VMware community. He is a vExpert and MVP on Windows PowerShell.
Read the rest of this entry »