Set's IOPS, as a filter, in PowerCLI

Set-IOPSLimit.ps1

filter Set-IOPSLimit {
    $_ | % {
        $DiskLimitIOPerSecond = 300
        # $DiskLimitIOPerSecond = -1 # Unlimited

        $vm = Get-VM -Name $_.Name
        $spec = New-Object VMware.Vim.VirtualMachineConfigSpec
        $vm.ExtensionData.Config.Hardware.Device |
         where {$_ -is [VMware.Vim.VirtualDisk]} | %{
            $dev = New-Object VMware.Vim.VirtualDeviceConfigSpec
            $dev.Operation = "edit"
            $dev.Device = $_
            $dev.Device.StorageIOAllocation.Limit = $DiskLimitIOPerSecond
            $spec.DeviceChange += $dev
        }

        $vm.ExtensionData.ReconfigVM_Task($spec)
    }
}