PowerShell: Monitoring DrainStatus of a Hyper-V Host & The Time Limited Value of Information In Beta & RC Era Blogs

I was writing some small PowerShell scripts to kick pause and resume Hyper-V cluster hosts and I wanted to monitor the progress of draining the virtual machines of the node when pausing it. I found this nice blog about Draining Nodes for Planned Maintenance with Windows Server 2012 discussing this subject and providing us with the properties to do just that.

It seems we have two common properties at our disposal: NodeDrainStatus and NodeDrainTarget.

image

So I set to work but I just didn’t manage to get those properties to be read. It was like they didn’t exist. So I pinged Jeff Wouters who happens to use PowerShell for just about anything and asked him if it was me being stupid and missing the obvious. Well it turned out to be missing the obvious for sure as those properties do no exist. Jeff told me to double check using:

Get-ClusterNode MyNode -cluster MyCluster | Select-Object -Property *

Guess what, it’s not NodeDrainStatus and NodeDrainTarget but DrainStatus and DrainTarget.

image

What put me off here was the following example in the same blog post:

Get-ClusterResourceType "Virtual Machine" | Get-ClusterParameter NodeDrainMoveTypeThreshold

That should have been a dead give away. As we’ve been using MoveTypeTresHold a lot the recent months and there is no NodeDrain in that value either. But it just didn’t register. By the way you don’t need to create the property either is exists. I guess this code was valid with some version (Beta?) but not anymore. You can just get en set the property like this

Get-ClusterResourceType “Virtual Machine” -Cluster MyCluster | Get-ClusterParameter MoveTypeThreshold

Get-ClusterResourceType “Virtual Machine” -Cluster MyCluster | Set-ClusterParameter MoveTypeThreshold 2000

So lessons learned. Trust but verify Smile.  Don’t forget that a lot of things in IT have a time limited value. Make sure that to look at the date of what you’re reading and about what pre RTM version of the product the information is relevant to.

To conclude here’s the PowerShell snippet I used to monitor the draining process.


Suspend-clusternode –Name crusader -Cluster warrior -Drain

Do
{
    Write-Host (get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -ForegroundColor Magenta    
    Sleep 1
}
until ((get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -ne "InProgress")

If ((get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -eq "Completed")
{
    Write-Host (get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -ForegroundColor Green
}

Which outputs

image

Understanding Virtual Machine Priority and Preemption Behavior

Introduction

By reading Aidan Finn his blog You Pause A Clustered Hyper-V Host And Low Priority VMs are QUICK MIGRATED! you will learn something about how virtual machine priorities work during the pausing and draining of a clustered Hyper-V host. They are either Live or quick migrated depending on the value of the MoveTypeThreshold cluster parameter for resources of the type “Virtual Machine”. By default it’s at 2000 and that happens to be the value of the virtual machine priority “Low”.

Changing this value can alter the default behavior. For example setting the MoveTypeThreshold value to 1000 using PowerShell

Get-ClusterResourceType “Virtual Machine” | Set-ClusterParameter MoveTypeThreshold 1000

makes sure that only VMs with a priority set to “No Auto Restart”  are quick migrated. The  low priority machines would than also live migrate where by default they quick migrate.

  • Virtual Machines with Priority equal to or higher than the value specified in MoveTypeThreshold will be moved using Live Migration.
  • Virtual Machines with Priority lower than the value specified in MoveTypeThreshold will be moved using Quick Migration.

Virtual Machine Priorities
3000 = High
2000 = Medium
1000 = Low
0 = Virtual machine does not restart automatically.

Another Scenario to be aware of  to avoid surprises

Note that al this also comes into play in other scenario’s. One of them is when you attempt to start a guest that requires more resources than available on the host. Preemption kicks in and the lower priority virtual machines go into a saved state.  If you didn’t plan for this it could be a bit of a surprise, causing service interruption. What’s also important to know is that preemption kicks in even when there is no chance that putting lower priority virtual machines into saved mode will free enough resources for (all) the VMs you’re trying to start. So that service interruption might do you no good. If this is the case the Low priority VMS come back up when there are sufficient resources left.  Do note however that the ones set top “No Auto Restart” remain in a saved state. Look below for an example on how this could happen.

How does this happen?

Let’s say you have a brand new VM that has gotten 16GB of RAM as requested by the business. When that large memory guest starts it will fail due to the fact that there are not enough memory resources available on the host that only has 16GB available. But as it attempts to start, the need for memory resources is detected and preemption comes into play. The guests with “Low” and “No Auto Restart” priorities are put into a saved state as the large memory VM has the default medium priority and the MoveTypeTreshold is at the default of 2000. You need to be ware of this behavior. Preemption kicks in and the machines are still saving while starting the large memory VM has already failed as they couldn’t free enough resources anyway.

image

The good new is that, as you can see below, is that the low priority guest starts again after starting the large memory guest has failed. No use keeping it saved as it can run and service customers. So the service interruption for this VM is limited but it does happen. Please also note that the guest set to No Auto Restart doesn’t come up again as it’s priority status says exactly that. So, this one becomes collateral damage.

image

As you can see it’s important to know how priorities and preemption work together and behave. It also good to know that changing the threshold come into play in more situations that just pausing & draining a host of during a fail over. While the cluster will try it’s best to keep as many VMs up and running you might have some unintended consequences under certain conditions. A good understanding of this can prevent you from being bitten here. So build a small cheap lab so you can play with stuff. This helps to gain a better understanding of how features work and behave. If you want to play some more, set the priority of the memory hungry VM to high you’ll see even more interesting things happen.

Monitoring Startup,Shutdown and restart of a Virtual machine With PowerShell 3.0

During scripting some maintenance PowerShell scripts for Hyper-V guests I felt the need for a more accurate way to monitor the startup of a virtual machine. Pings, telnet to a known open port it all doesn’t do the job accurately enough as I want to know when CTRL+AL+DEL appears on the screen. So I pinged Jeff Wouters who told me I could monitor Get-VM -Name DC01 | Get-VMIntegrationService  to detect when PrimaryStatusDescription goes to “OK”.

Now when you look at the Integration services there are 5 of them.

image

Which one is the best to use for our purpose? Well,I tested them out and after some experimenting with the various services I concluded that the PrimaryStatusDescription of the  Key-Value Pair Exchange works best for this purpose. All others become available a bit to soon in the process of starting a VM, which seems logical.

Monitor a starting virtual machine

So how to use this in a script? We’ll here’s a snippet to monitor the boot process of a guest.

$Vm = Get-VM "MyVM"
start-VM "$Vm"
#This means the VM is now shutting down ...    
$Counter = 0
$ProgressCount = 0
Do
{    
    $Operational = Get-VM -Name $VM | Get-VMIntegrationService -Name "Key-Value Pair Exchange"
    $Counter = $Counter + 1 
    $ProgressCount =  $ProgressCount +1
    $PercentComplete = ($ProgressCount * 20)
    Write-Progress -Activity "$VM" -status "VM starting up: $Status - Progressbar indicates activity, not a percent of completion: ($Counter Seconds)"  -percentComplete ($PercentComplete / 100 *100)
    if ($PercentComplete -gt 90) {$ProgressCount = 0}
    sleep 1
}
While ($Operational.PrimaryStatusDescription -ne "OK")
$Status = (Get-VM -Name $VM | Get-VMIntegrationService -Name "Key-Value Pair Exchange").PrimaryStatusDescription
Write-Progress -Activity "VM $VM is up and running" -status "VM status: $Status - We're done here. Completed in a total of $Counter seconds."  -percentComplete (100)

 

Monitor a stopping virtual machine

Likewise, sometime we want to monitor a VM shutting down, which is the same code as above but with reverse logic.

$Vm = Get-VM "MyVM"
stop-VM "$Vm"
$Counter = 0
$ProgressCount = 0
#This means the VM is now shutting down  in the retart cycle ...    
   Do
   {            
    $Operational = Get-VM -Name $Vm | Get-VMIntegrationService -Name "Key-Value Pair Exchange"
    $Counter = $Counter + 1 
    $Status = (Get-VM -Name $Vm | Get-VMIntegrationService -Name "Key-Value Pair Exchange").PrimaryStatusDescription
    $ProgressCount =  $ProgressCount + 1
    $PercentComplete = ($ProgressCount * 20)
    Write-Progress -Activity "$VM" -status "VM shutting down : $Status - Progressbar indicates activity, not a percent of completion: ($Counter Seconds)"  -percentComplete ($PercentComplete / 100 *100)
    if ($PercentComplete -gt 90) {$ProgressCount = 0}
    sleep 1
   }
   While ($Operational.PrimaryStatusDescription -eq "OK")
   $Status = (Get-VM -Name $Vm | Get-VMIntegrationService -Name "Key-Value Pair Exchange").PrimaryStatusDescription
   Write-Progress -Activity "VM $Vm has now been shutdown" -status "VM status: $Status - We're done here. Completed in a total of $Counter seconds."  -percentComplete (100)

Monitor a restarting a virtual machine.

When in a PowerShell script you want to monitor progress of a virtual machine restarting you can combine both. You monitor shutdown and you monitor startup.

$VmThatRestarts = Get-VM "MyVM"
#Restart the VM
#This means the VM is now shutting down  in the retart cycle ...
 $Counter = 0
 $ProgressCount = 0
Do
{            
    $Operational = Get-VM -Name $Vm | Get-VMIntegrationService -Name "Key-Value Pair Exchange"
    $Counter = $Counter + 1 
    $Status = (Get-VM -Name $Vm | Get-VMIntegrationService -Name "Key-Value Pair Exchange").PrimaryStatusDescription
    $ProgressCount =  $ProgressCount + 1
    $PercentComplete = ($ProgressCount * 20)
    Write-Progress -Activity "$VM" -status "VM restarting - Shutdown phase : $Status - Progressbar indicates activity, not a percent of completion: ($Counter Seconds)"  -percentComplete ($PercentComplete / 100 *100)
    if ($PercentComplete -gt 90) {$ProgressCount = 0}
    sleep 1
}
While ($Operational.PrimaryStatusDescription -eq "OK")
$Status = (Get-VM -Name $Vm | Get-VMIntegrationService -Name "Key-Value Pair Exchange").PrimaryStatusDescription
Write-Progress -Activity "VM $Vm has now been shutdown in restart cycle" -status "VM status: $Status - VM has shut down in $Counter Seconds"  -percentComplete (100)
   
#Any thing worthwhile is worth adding 1 second of waiting for good measure :-)
Sleep 1

#This means the VM is now starting  ...    
$ProgressCount = 0
Do
{    
    $Operational = Get-VM -Name $VM | Get-VMIntegrationService -Name "Key-Value Pair Exchange"
    $Counter = $Counter + 1 
    $ProgressCount =  $ProgressCount +1
    $PercentComplete = ($ProgressCount * 20)
    Write-Progress -Activity "$VM" -status "VM restarting - Startup phase: $Status - Progressbar indicates activity, not a percent of completion: ($Counter Seconds)"  -percentComplete ($PercentComplete / 100 *100)
    if ($PercentComplete -gt 90) {$ProgressCount = 0}
    sleep 1
}
While ($Operational.PrimaryStatusDescription -ne "OK")
$Status = (Get-VM -Name $VM | Get-VMIntegrationService -Name "Key-Value Pair Exchange").PrimaryStatusDescription
Write-Progress -Activity "VM $VM is up and running again" -status "VM status: $Status - We're done here. Completed in a total of $Counter seconds."  -percentComplete (100)

Note that in all the above snippets  I’ve thrown some logic in to us the progress bar as an activity bar as I know of no way to calculate real % done in a startup, shutdown, restart process. It looks something like this in ISE

image

or like this in a PowerShell prompt

image

Checking Host Integration Services Version on all Nodes of A Windows Server 2012 Hyper-V Cluster With PowerShell

It’s important to keep our Hyper-V cluster hosts and the virtual machines running on them up to date. Whilst we have great and free solutions to achieve this there are some things missing like centralized reporting on the Integration Services component version running on all of the nodes in a cluster and way to upgrade all the virtual machines to version running on the host. This post deals with the first issue.

Before we upgrade the Integration Services components on the virtual machines we always check if all nodes in the cluster are on the same version themselves. Sure this should not happen if you mange them right but my world isn’t perfect. So trust but verify.With cluster sizes now up to 64 nodes it’s ever more important to keep an eye on them. But even for smaller cluster the task of determining the Integration Services components manually via the GUI, event viewer and/or registry is rather tedious. Out of sync Integration Services components can be troublesome and cause many issues and if you have out of sync virtual machines, imagine the extra mess you’ll be in when even the cluster nodes are running different versions.

To make live easier I threw a little PowerShell script together to check the host Integration Services component version on all nodes of a Window Server 2012 Hyper-V Cluster With PowerShell. I’m far from a PowerShell guru, but you’ll see that you can do a lot of things  done even if you’re not. I’m sharing it here for you to use, adapt for your own needs and get some inspiration. It basically allows you to optionally pass an expected version of the IS components and a cluster name like this

CheckHyperVClusterHostsICVersion -Version 6.2.9200.16433 -cluster "MyClusterName"

It does the following:

  • It will list per Integration Services component version found on cluster nodes what version was found on what nodes. This gives you a nice overview. I hope this never becomes to much of a list in your clusters.
  • If you don’t specify a cluster it will try to connect to the cluster to which the host you’re running on belongs, if any.
  • If the host does not belong to a cluster it will just provide feedback on the IS version of that Hyper-V host you’re running the script on.

Here’s a screen shot of when you run this on a none clustered host, without Hyper-V installed:

image

This is the result of running it against a well maintained cluster without any parameters that has been updated with KB2770917:

image

The same but now with the expected version and cluster name passed as parameters

image

So, there you go, I hope you find it useful.

#===========================================================
# # Microsoft PowerShell Source File 
# 
# NAME:    CheckISCOnNodesOfHyperVCluster.ps1
# VERSION:    1.0.0.0

# AUTHOR:    Didier Van Hoye
# DATE :    17/11/2012
# 
# COMMENT:     This script is intended to be run 
#              against Windows Server 2012 and assumes
#            the use of PowerShell 3.0
#            The parameters are optional but if you
#            leave out some the remainder should be named.
# # =======================================================
 
cls
$ErrorActionPreference = "Stop"

 
function CheckHyperVClusterHostsICVersion
{
    Param
    (
        #Param help description
        [Version]
        $ExpectedISCVersion,
        #Param help description
        [String]
        $Cluster
    )

    Write-Host "This script will check the IS components on all nodes of a cluster." -ForegroundColor Green
 
    If ($ExpectedISCVersion) {Write-Host "You specified the expected IS component version to be $ExpectedISCVersion" -ForegroundColor Green}
    Else {Write-host "You did not specify an expected IS component version." -ForegroundColor Green}
    
    If ($Cluster)
    {
        Try
        {
            $ClusterObject= Get-Cluster -Name $Cluster
        }
        Catch
        {     
            Write-Host "We cannot contact the cluster you specified"
        }
    }
    Else
    {    
        write-Host "`n`n"
        Write-host "You did not specify a cluster to connect to. We'll use the cluster to which the node this script is running on belongs if any." -ForegroundColor Yellow
        write-Host "`n`n"
  
        Try
        {
            $ClusterObject = Get-Cluster
        }
  
        Catch
        {
            $LocalHost = $env:computername
            Write-Host
            Write-Host "The current node ($LocalHost) is not a member of a cluster. As a courtsey to you we'll check the IS components for current host" -foregroundcolor Magenta
            Write-Host
        }
 
    }
  
    If ($ClusterObject) {$ToCheck= "the nodes of cluster $ClusterObject"} Else { $ToCheck = "server $env:computername"}
 
    write-Host "Attempting to running Integration Components version check on" $ToCheck -ForegroundColor Green
    Write-Host


    If ($ClusterObject)
    {

        $ClusterNodes = Get-Clusternode -cluster $ClusterObject.Name
        
        #Declare an hashtable to hold all host/IS version values. The hosts are the key here.
        $HostISVersions = @{}
 
        foreach ($ClusterNode in $ClusterNodes)
        {
            Try
            {
                 $HostISVersions[$ClusterNode.Name]=Get-ItemProperty "HKLM:SOFTWAREMicrosoftWindows NTCurrentVersionVirtualizationGuestInstallerVersion" | select -ExpandProperty Microsoft-Hyper-V-Guest-Installer
            }
            Catch
            {
            Write-Host "We could not determine the version of the Integration Services on this host, probably due to this not being a Hyper-V host" -ForegroundColor Orange
            Write-Host "We'll check this for you right now" -ForegroundColor Orange
            $HyperVFeature = Get-WindowsFeature Hyper-V
            If ($HyperVFeature.Installstate -eq "Installed")
            {
              Write-Host "Hyper-V seems to be installed on this node. Something else is wrong." -ForegroundColor Red
            }
            Else
            {
                Write-Host "Hyper-V is indeed not installed on this node." -ForegroundColor Orange
            }
            }
        }
         #Use GetEnumerator or thise sorting thing doesn't work out well on an hash tabel :-)
        $UniqueIcVersions = $HostISVersions.GetEnumerator() | Sort-Object -Property Value -Unique
 
        Write-Host "We've found " $UniqueIcVersions.count "versions on the" $HostISVersions.count "nodes of your cluster" $ClusterObject.Name
 
        ForEach ($IcVersion in $UniqueIcVersions )
        {
            $Counter = 1
            $IcVersionValue = $IcVersion.value
            "IC version " + $IcVersion.value + " is found in:"
            foreach ($Key in ($HostISVersions.GetEnumerator()| Where-Object { $_.value -eq $IcVersionValue}))
            {
                "`t" + "$Counter : " + $Key.Name
                $Counter= $Counter + 1
            }
 
            If ($ExpectedISCVersion)
            {
               
                $CompareVersions = ([Version]$IcVersion.Value).CompareTo([Version]$ExpectedISCVersion)
                        
                switch ($CompareVersions)
                {
                    0 {Write-Host "This version ($IcVersionValue) is equal to the expected version ($ExpectedISCVersion)." -ForegroundColor Green}
                    1 {Write-Host "This version ($IcVersionValue) is higher than the expected version ($ExpectedISCVersion). Please ensure all hosts run the same IC version level." -ForegroundColor Yellow}
                    -1 {Write-Host "This version ($IcVersionValue) is lower than the expected version ($ExpectedISCVersion). Please ensure all hosts run the same IC version level." -ForegroundColor Red}
                }
            }

        }
    }

    Else
    {
        Try
        {
            $HostIcVersion = Get-ItemProperty "HKLM:SOFTWAREMicrosoftWindows NTCurrentVersionVirtualizationGuestInstallerVersion" | select -ExpandProperty Microsoft-Hyper-V-Guest-Installer
            Write-Host "The IS component version on server $localhost is $HostIcVersion"
            If ($ExpectedISCVersion)
            {
               
                   $CompareVersions = ([Version]$HostIcVersion).CompareTo([Version]$ExpectedISCVersion)
                        
                switch ($CompareVersions)
                {
                0 {Write-Host "This version ($HostIcVersion) is equal to the expected version ($ExpectedISCVersion)." -ForegroundColor Green}
                1 {Write-Host "This version ($HostIcVersion) is higher than the expected version ($ExpectedISCVersion). Please check if you need to downgrade your host or if the expected version is correct." -ForegroundColor Yellow}
                -1 {Write-Host "This version ($HostIcVersion) is lower than the expected version ($ExpectedISCVersion). Please check if you need to upgrade your host or if the expected version is correct." -ForegroundColor Red}
                }
            }
        }
        Catch
        {
            Write-Host "We could not determine the version of the Integration Services on this host, probably due to this not being a Hyper-V host" -ForegroundColor yellow
            Write-Host "We'll check this for you right now" -ForegroundColor yellow
            $HyperVFeature = Get-WindowsFeature Hyper-V
            If ($HyperVFeature.Installstate -eq "Installed")
            {
                Write-Host "Hyper-V seems to be installed on this node. Something else is wrong." -ForegroundColor Red
            }
            Else
            {
                Write-Host "Hyper-V is indeed not installed on this node." -ForegroundColor yellow
            }
        }
    }
}
 
CheckHyperVClusterHostsICVersion -Version 6.2.9200.16433 -cluster "MyClusterName"