As most of you know and probably experienced from time to time: when a Virtual Machine’s CD-drive is connected to an ISO-file on one of your Datastores or even connected to the physical drive of your ESX-host the migration due VMotion of a Virtual Machine will not work.

Normally this isn’t really a problem except if you put a ESX-host in Maintenance mode and Virtual Center will simply not tell you why the Maintenance mode process is hanging or even giving a time-out after 15 minutes for no obvious reason. Most of the times it’s a Virtual Machine which has a CD-drive connected to an ISO file. A waste of time if you ask me.

So to prevent this from happening I’ve written a simple PowerShell oneliner/script disconnect these CD-drives from the ISO-files or from the physical drives and set them to Client-drives which is ok for VMotion:

(Get-VM -Location  Get-VMHost "your.esx.host")) | `
ForEach ( $_ ) { Get-CDDrive $_ | `
Where { $_.IsoPath.Length -gt 0 -OR $_.HostDevice.Length -gt 0 } | `
Set-CDDrive -NoMedia -Confirm:$False }

Instead of executing this just on one host you can also execute this for your entire cluster:

(Get-VM -Location  Get-Cluster "Your Cluster Name")) | `
ForEach ( $_ ) { Get-CDDrive $_ | `
Where { $_.IsoPath.Length -gt 0 -OR $_.HostDevice.Length -gt 0 } | `
Set-CDDrive -NoMedia -Confirm:$False }

Or ofcourse, by Datacenter:

(Get-VM -Location  Get-Datacenter "Your Datacenter Name")) | `
ForEach ( $_ ) { Get-CDDrive $_ | `
Where { $_.IsoPath.Length -gt 0 -OR $_.HostDevice.Length -gt 0 } | `
Set-CDDrive -NoMedia -Confirm:$False }

It’s as easy as that, now there will be no Virtual Machine interrupting your VMotions anymore and you can put your ESX hosts in maintenance mode without any problems

Cheers!

It’s not hard to create a PowerShell script to list your current snapshots, but of course it’s a nice challenge to create a oneliner that’ll take care of this.

I’ve created several oneliners with different output, for instance: this one is to show snapshots of your total VMware infrastructure:

Get-VM | Sort Name | Get-Snapshot | Where { $_.Name.Length -gt 0 } | Select
VM,Name,Description,Created

While in fact in the organisation I work for we have several locations throughout the country and several VMware ESX Servers running on each one which we’ve divided in different Datacenters in our VMware Infrastructure.

So for instance you can also use the following line to list all Snapshots in a specific Datacenter:

Get-Datacenter -Name "Your Datacenter" | Get-VM | Sort Name | Get-Snapshot | 
Where { $_.Name.Length -gt 0 } | Select VM,Name,Description,Created

Or just for one specific cluster:

Get-Cluster "Cluster Name" | Get-VM | Sort Name | Get-Snapshot | Where
{ $_.Name.Length -gt 0 } | Select VM,Name,Description,Created

All of these oneliners give somewhat the same output, which looks like this (company sensitive names are sensored, sorry )

You can also add several other cmdlets to change the output of the result data, such as  ConvertTo-HTML or Out-GridView (if you use PowerShell 2.0 already).

When using NFS for your datastores on your SAN (eg. NetApp) and you resize your datastore on the fly it always takes a while before the ESX/vSphere servers refresh the datastore so you can see the new size of the volume.

This can be annoying when you want to create a VM on one of these volumes and ESX still thinks the volume is too small because it hasn’t refreshed it’s datastores yet. Normally I would pick one ESX server where I want to put the VM on for starters and refresh the NFS volume which I want to use:

Ofcourse I wanted to make it easier for myself so I wrote a little PowerShell script to refresh the datastores on all ESX Servers in our Cluster. I think it’s also possible to make a oneliner out of this and I will try to create one and if I succeed I’ll post it again

$vcHost = "virtual.center.host"
$vcClusterName = "Your ClusterName"
$vcUser = "username"
$vcPass = "password"

$vcServer = Connect-VIServer -Server:$vcHost -User:$vcUser -Password:$vcPass -WarningAction:SilentlyContinue

$vmHosts = Get-Datacenter | Get-Cluster -Name:$vcClusterName | Get-VMHost | Sort

ForEach ($vmHost in $vmHosts) {
    If (Get-VMHostStorage -VMHost:$vmHost -Refresh -ErrorAction:SilentlyContinue -WarningAction:SilentlyContinue) {
        Write-Host $vmHost.Name," host storage information refreshed"
    } else {
        Write-Host $vmHost.Name," host storage refresh failed!"
    }
}

Disconnect-VIServer -Server:$vcServer -Confirm:$false

After the script has been running the datastores on all your ESX-servers in the cluster will be refreshed so all resizes  of your NFS volumes on your SAN will be visible and “active”.