VMM 2012 – Cluster Overcommit algorithm

The Cluster overcommit algorithm can be used to explain when VMs will not start on a cluster (even when it appears there is enough memory to start),


VMM Error 25122

This error can occur after manually adding a Hyper-V cluster to VMM 2012 R2. It appears to occur because the Cluster Virtual IP address exists in the IP pool


VMM 25122

The script is below, credits to vNikkas who has also blogged about this (there was another version floating around last year too I believe).

$ID = Enter the ID found in the error message (you can copy the text, paste into notepad and then copy the ID

$IPPoolName = Enter the name of the IP pool associated with the error message

If (-not (Get-Module virtualmachinemanager)) {
Import-Module virtualmachinemanager }

$IP = Get-SCIPAddress | Where-Object {$_.ID -eq $ID}
$IPPool = Get-SCStaticIPAddressPool -Name $IPPoolName
# Looking up DNS Name based on IP Address
$VMHostClusterName = [System.Net.Dns]::GetHostbyAddress($IP.Name)
$VMHostCluster = Get-SCVMHostCluster -Name $VMHostClusterName.HostName

# Giving the IP Address back to the IP Pool
Get-SCIPAddress -IPAddress $IP | Revoke-SCIPAddress

# Allocating the IP Address to the VM Host Cluster
Grant-SCIPAddress -GrantToObjectType HostCluster -GrantToObjectID $VMHostCluster.ID -IPAddress $IP.Name -StaticIPAddressPool $IPPool -Description $VMHostCluster.Name

New Book on Hyper-V Security

If your interested in securing your Hyper-V hypervisor then check out a new book by Eric Siron

Eric's Technical Outlet

My second book is now available for purchase. Its name is Hyper-V Security. It’s a short-form book with only eight chapters. The first six are related to the host, the hypervisor, and the guests. The final two chapters were written by Andrew Syrewicze and cover security in System Center Virtual Machine Manager.

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