Hyper-V ID Hash Table

In Hyper-V, one of the challenges (at least that I've run into) has to do with naming. In addition to a name, Hyper-V objects such as virtual machines, are identified with a GUID. Most of the VM-related PowerShell cmdlets will let you specify a virtual machine name. But sometimes you'll run across the GUID and wonder what is the corresponding virtual machine. Here's a WMI query using Get-CIMInstance that shows the currently open terminal connections to a few virtual machines.


PS C:\> get-ciminstance -Namespace root\virtualization -class msvm_terminalconnection | Select connectionID,installdate

The GUID in the connection ID corresponds to a virtual machine. Here's my approach for "translating" the GUID to a name. Every VM has an ID.


PS C:\> (get-vm chi-dc01).id

Guid
----
f7d3ad8b-6329-43a3-991e-8a630a94ec40


There is also an VMID property but that is merely an alias to ID. As you can see, the ID is a GUID object so to get just the GUID string takes another step.


PS C:\> (get-vm chi-dc01).id.guid
f7d3ad8b-6329-43a3-991e-8a630a94ec40


Now that I know how to capture this information, I can build a "lookup" object using a hash table.


PS C:\> Get-VM | Group-Object -property {$_.ID.GUID} -AsHashTable -AsString


Here's what I end up with:

Naturally, it makes more sense to save this to a variable.


PS C:\> $vmhash = Get-VM | Group-Object -property {$_.ID.GUID} -AsHashTable -AsString


The VM GUID is the key and the VM object is the value. I can get items a few ways.


PS C:\> $vmhash.'13876524-bfd8-40a1-95e3-926e37acfbab'

Name State CPUUsage(%) MemoryAssigned(M) Uptime Status
---- ----- ----------- ----------------- ------ ------
CHI-FP01 Running 0 761 03:36:29 Operating normally


Now I can add some logic to my Get-CIMInstance command to resolve the GUID to the VM name.


$vmhash = Get-VM | Group-Object -property {$_.ID.GUID} -AsHashTable -AsString

$guid = $rx.Match($_.ConnectionID).Value
$vmhash.item($guid).Name
}}


I also tweaked a few other properties. I extracted the GUID using a regular expression and then found the corresponding entry in the hash table. I could have added a little extra logic to test if the GUID existed as a key but I decided to just plow ahead.

The hash table makes it very easy now to resolve virtual machine GUID's to a user friendly name.

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