Changing disk.enableUUID on multiple VMs

[glwnieves]

Hello,

I am trying to update multiple VMs that have been affected by a previous VMware bug that caused the disk.enableUUID value to be missing from a bunch of VMs.

Here is the bug in case anyone wants to reference it:

VMware Knowledge Base

I needed a way to run this against multiple machines at the same time. I was able to piece together this script from a few different scripts I have used in the past.

# Load PowerCLI Plugin and connect to VCenter Server
Import-Module VMware.VimAutomation.Core -ErrorAction SilentlyContinue
connect-viserver VCENTERSERVERNAME

# Clear Report.csv Values From Previous Run
Clear-Content -Path .\report.csv

# CSV file with a column named vmName
Import-Csv -Path .\vmnames.csv -UseCulture -PipelineVariable row |
ForEach-Object -Process {
    $vm = Get-VM -Name $row.vmName

# Set disk.EnableUUID to True on all VMs listed in vmnames.csv
$vm | New-AdvancedSetting -name disk.EnableUUID -Value 'TRUE' -Force -Confirm:$false | Export-Csv -Path .\report.csv -NoTypeInformation -UseCulture -Append}

When I ran this without the -Append value at the end of the Export-Csv I only got the last VM the script ran against. After, I put append it would export all the results. However, I noticed that since I was appending if I didn't manually clear the file it would keep the previous results as well. So, I added the Clear-Content line to clear the file before it runs.

Also, I was getting prompted to confirm the value change for each individual VM so I added the -Confirm:$false value as well.

Is there a cleaner way of accomplishing what I want or do you think this is good as is?

My last question is can I change the disk.enableUUID value while the VM is running or do I need to power them off first? I know it won't take effect until the VM is powered down and on but I wasn't sure if it would cause any major issues to a running VM. I see can't change it from the Configuration Parameters in the Edit Settings within the GUI when it's running so I was concerned.

[LucD · Accepted solution]

I'm afraid that is because you are doing the Export-Csv inside the Foreach-Objct block, meaning you overwrite the CSV at each loop.

You can move the Export-Csv outside the loop.

# Load PowerCLI Plugin and connect to VCenter Server
Import-Module VMware.VimAutomation.Core -ErrorAction SilentlyContinue
connect-viserver VCENTERSERVERNAME

# Clear Report.csv Values From Previous Run
Clear-Content -Path .\report.csv

# CSV file with a column named vmName
Import-Csv -Path .\vmnames.csv -UseCulture -PipelineVariable row |
ForEach-Object -Process {
    $vm = Get-VM -Name $row.vmName

# Set disk.EnableUUID to True on all VMs listed in vmnames.csv
  $vm | New-AdvancedSetting -name disk.EnableUUID -Value 'TRUE' -Force -Confirm:$false
} | Export-Csv -Path .\report.csv -NoTypeInformation -UseCulture

[glwnieves]

That worked great, thanks! Do you know if I execute the script to add the disk.enableuuid value while the VM is running if it will break anything? As I said before I know it won't take affect until the VMs are power cycled but I'm trying to update this value on multiple VMs. I'm just concerned about something crashing.

[LucD]

The KB you referenced earlier does say to power off the VM.
So I think it would be advisable to follow that advice

[glwnieves]

Fair enough. Thanks again for your help. I did reach out to support and this was their response for anyone that is curious:

I understand from the case notes that you have queries in regards to the script for DIsk UUID 

If the script is run on a powered on VM, it would not apply the change as the Host would be holding a lock on the vmx file.

As mentioned by you, this would apply only after a power cycle on the VM and even if script is ran on powered on VMs, it should cause no issues.

I have not tested this script on a Production setup, I would recommend first trying on a couple of VMs and then applying to rest of them, just to be sure.