Automating configuration of a scratch location with PowerCLI

Quite often the modern ESXi servers come with no local storage and ESXi is normally installed on SD card.

As per VMware KB1033696 the SD card can't be used to store scratch partition. The main purpose of the scratch partition is to store logging files and to provide space for vm-support output.

So, the normal practice is to use shared storage (VMFS/NFS) as a scratch location. The problem is that the configuration of the scratch location is not automated in the existing vSphere. So you have to manually create folder for each of the ESXi host and configure each ESXi host to use that folder.
This can be quite time-consuming and boring tasks when you have to do it for hundred of servers.

To make things worse Host Profiles do not let you configure scratch location too.

I had some time last week and thought it was a good chance to have fun with PowerCLI and automate the scratch configuration for ESXi hosts.

So here is overview of what the script does:

1. Connects to vCenter
2. Collects the list of ESXi hosts in the cluster. Very often storage is not shared across multiple compute clusters so I decided to use cluster, not a datacenter, as a configuration target.
3. Checks if there is a designated scratch folder for each of the clusters and creates if it doesn't exist
4. Checks if the ESXi host configured with scratch location and if it points to the right datastore and folder.
5. If ESXi is not configured yet or points to the wrong directory the correct setting will be applied.
6. Provides a list of the ESXi servers to be rebooted for the configuration change to take effect

There are a couple of thing you have to do before running the script:

• Identify the datastore to be used to store scratch folders
• In that datastore create a folder where the script will create a scratch folder per each host 

 The syntax is as following:

.\scratch.ps1 -vCenter vCenter_Name -cluster Cluster_Name -datastore Datastore_Name -folder Folder_Name

for example

.\scratch.ps1 -vCenter lab-vc-01.lab.local -cluster HA -datastore ISO -folder Scratch

* I had to add folder as input parameter because I couldn't make the script land into the correct folder with New-PSdrive commandlet

You can go even further by taking advantage of Windows Task Scheduler to run this script on a daily basis to ensure all servers are consistently configured.

Let me know how it worked for you.

	#Collect the vCenter, Cluster and scratch_datastore
	Param([String]$vCenter, [String]$Cluster, [String]$Datastore, [String]$Folder)
	#Function to use multiple colors in one command
	function Write-Color([String[]]$Text, [ConsoleColor[]]$Color) {
	for ($i = 0; $i -lt $Text.Length; $i++) {
	Write-Host $Text[$i] -Foreground $Color[$i] -NoNewLine
	}
	Write-Host
	}
	#defining array variables
	$vmhost_array =@()
	$dir = @()
	$reboot_servers = @()
	#Validating input
	if (!$vCenter){
	Write-Color -Text "Please provide valid vCenter name using ","'-vCenter' ","option, exiting.." -Color Gray,Red,Gray
	exit
	}
	if (!$Cluster){
	Write-Color -Text "Please provide valid cluster name using ","'-Cluster' ","option, exiting.." -Color Gray,Red,Gray
	exit
	}
	if (!$Datastore){
	Write-Color -Text "Please provide valid Datastore name using ","'-Datastore' ","option, exiting.." -Color Gray,Red,Gray
	exit
	}
	if (!$Folder){
	Write-Color -Text "Please provide valid scratch folder name using ","'-Folder' ","option, exiting.." -Color Gray,Red,Gray
	exit
	}
	cls
	#Getting the path of the script
	$scriptPath = split-path -parent $MyInvocation.MyCommand.Definition
	#Collecting credentials for vCenter
	do {$user = Read-Host -Prompt 'Enter username for vCenter'
	$pass = Read-Host -AsSecureString -Prompt 'Enter password for vCenter'
	$cont = Read-Host -Prompt 'Type y to continue'}
	while ($cont -ne 'y')
	$cred = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList $user, $pass
	#Connecting to vCenter server
	Write-Color -Text "`nConnecting to ", $vCenter -Color Gray, Red
	Connect-VIserver -Server $vCenter -Credential $cred | Out-Null
	#Validating connection to vCenter
	if(!$DefaultVIServers){
	Write-Color -Text "`nConnection to ",$vCenter," failed, exiting.." -Color Yellow,Red,Yellow
	exit
	} elseif($DefaultVIServer.name -ne $vCenter){
	Write-Color -Text "Connected to wrong vCenter ", $DefaultVIServer.name ", exiting.." -Color Yellow,Red,Yellow
	} else {
	Write-Color -Text "Connection to vCenter ", $vCenter, " succeeded" -Color Green,Red,Green
	Write-Host
	}
	#Getting the list of the ESXi hosts in the $Cluster
	$vmhost_array = get-cluster -name $cluster | Get-VMhost
	#Getting Scratch datastore UUID
	$ds_view = Get-View (Get-View (Get-VMHost -Name $vmhost_array[0]).ID).ConfigManager.StorageSystem
	foreach ($vol in $ds_view.FileSystemVolumeInfo.MountInfo) {
	if ($vol.Volume.Name -eq $datastore) {
	$datastore_uuid = $vol.Volume.Uuid
	}
	}
	#Mounting datastore to be used as a scratch location
	New-PSDrive -Name "DS" -Root \ -PSProvider VimDatastore -Datastore (Get-VMHost -Name $vmhost_array[0] | Get-Datastore $datastore) | out-null
	Set-Location DS:\$folder
	#Collect the list of the folders
	$dir = dir
	#Check if the scratch folders exist for the ESXi hosts and create missing folders
	Foreach ($vmhost in $vmhost_array)
	{
	If ($dir.name -contains $vmhost.name){
	Continue
	}
	else{
	Write-Color -Text "`n Creating scratch folder for ", $vmhost -Color Green,Red
	mkdir $vmhost | out-null
	}
	}
	#Check if the ESXi host is already configured with correct scratch location
	Foreach ($vmhost in $vmhost_array){
	$row = '' | Select Server_Name
	$configured_scratch = (Get-VMhost $vmhost | Get-AdvancedSetting -Name "ScratchConfig.ConfiguredScratchLocation").value
	$current_scratch = (Get-VMhost $vmhost | Get-AdvancedSetting -Name "ScratchConfig.CurrentScratchLocation").value
	$correct_scratch = "/vmfs/volumes/"+$datastore_uuid+"/"+$folder+"/"+$vmhost
	# Write-Host "`n Correct scratch is" $correct_scratch
	# Write-Host "`n Configured Scratch on" $vmhost "is" $configured_scratch
	# Write-Host "`n Current Scratch on" $vmhost "is" $current_scratch
	If (($configured_scratch -eq $correct_scratch) -and ($current_scratch -eq $correct_scratch)) {
	Write-Color -Text "`n ESXi host ", $vmhost, " was already configured with the correct scratch location" -Color Green,Red,Green
	} elseif($configured_scratch -eq $correct_scratch) {
	Write-Color -Text "`n The ESXi host", $vmhost, " was already configured correctly, `n but it hasn't been restared after the configuration change" -Color Yellow,Red,Yellow
	$row.Server_Name = $vmhost.Name
	$reboot_servers += $row
	} else {
	Get-VMhost $vmhost | Get-AdvancedSetting -Name "ScratchConfig.ConfiguredScratchLocation" |Set-AdvancedSetting -Value $correct_scratch -Confirm:$false |out-null
	Write-Host -Fore:Red "`n ESXi host" $vmhost "is configured with the correct scratch location"
	$row.Server_Name = $vmhost.Name
	$reboot_servers += $row
	}
	}
	#Provide output with the list of ESXi servers to be rebooted for the configration change to take effect
	Write-Host -Fore:Green "`n The configuration of the scratch location for ESXi servers in cluster" $cluster "is complete"
	Write-Host -Fore:Green "`n The following ESXi hosts have to be rebooted for the configuration change to take effect:"
	foreach ( $server in $reboot_servers ) {
	Write-Host -Fore:Red `n $server.Server_Name
	}
	#Exporting the list of ESXi hosts to be rebooted
	$exportfilename = "Servers_to_reboot.csv"
	$exportfilepath = Join-Path -Path $scriptPath -ChildPath $exportFileName
	$reboot_servers | Export-Csv -Path $exportFilePath -NoTypeInformation -Force
	Write-Host "`n This list of these servers has also been exported to" $exportfilepath
	#Change location back to original
	Set-Location $scriptPath
	#Disconnecting from vCenter
	Disconnect-viserver -Confirm:$false

view raw scratch.ps1 hosted with ❤ by GitHub