LucD notes

Lately I have been playing around with the new Storage related features in vSphere 5. One of the novelties is that you can now unmount a VMFS datastore and detach a SCSI LUN through the API.
To be able to unmount a datastore, some conditions have to be met. In the vSphere Client you get an informative popup that tells what is prohibiting the datastore unmount. If not all conditions are met, you can not continue with the unmount.

Nice feature, but what for those of us that want to automate this ?

Update October 28th 2012: Take into account that the datastorecluster is not connected to a host that is part of a cluster. Skip the HA heartbeat test.

Update April 23th 2012: Use the RetrieveDasAdvancedRuntimeInfo method to find the actual datastores that are used for the heartbeat.

What to look for ?

From the popup, it is quite obvious what specific feature can prohibit the unmount of a datastore.

But if you look at Cormac’s post called What could be writing to a VMFS when no Virtual Machines are running?, there are a couple of other settings that might influence the ability to unmount a datastore.

In Cormac’s post you’ll find that a Distributed Virtual Switch configuration file or the presence of a scratch partition might also cause IO that would prevent a datastore unmount.

So I decided to expand the function with a check for those 2 additional causes.

The script

function Get-DatastoreUnmountStatus{
  <#
.SYNOPSIS  Check if a datastore can be unmounted.
.DESCRIPTION The function checks a number of prerequisites
  that need to be met to be able to unmount a datastore.
.NOTES  Author:  Luc Dekens
.PARAMETER Datastore
  The datastore for which you want to chekc the conditions.
  You can pass the name of the datastore or the Datastore
  object returned by Get-Datastore
.EXAMPLE
  PS> Get-DatastoreUnmountStatus -Datastore DS1
.EXAMPLE
  PS> Get-Datastore | Get-DatastoreUnmountStatus
#>
  param(
    [CmdletBinding()]
    [Parameter(Mandatory=$true,ValueFromPipeline=$true)]
    [PSObject[]]$Datastore
  )

  process{
    foreach($ds in $Datastore){
      if($ds.GetType().Name -eq "string"){
        $ds = Get-Datastore -Name $ds
      }
      $parent = Get-View $ds.ExtensionData.Parent
      New-Object PSObject -Property @{
        Datastore = $ds.Name
        # No Virtual machines
        NoVM = $ds.ExtensionData.VM.Count -eq 0
        # Not in a Datastore Cluster
        NoDastoreClusterMember = $parent -isnot [VMware.Vim.StoragePod]
        # Not managed by sDRS
        NosDRS = &{
          if($parent -is [VMware.Vim.StoragePod]){
            !$parent.PodStorageDrsEntry.StorageDrsConfig.PodConfig.Enabled
          }
          else {$true}
        }
        # SIOC disabled
        NoSIOC = !$ds.StorageIOControlEnabled
        # No HA heartbeat
        NoHAheartbeat = &{
          $hbDatastores = @()
          $cls = Get-View -ViewType ClusterComputeResource -Property Host |
          where{$_.Host -contains $ds.ExtensionData.Host[0].Key}
          if($cls){
            $cls | %{
              (                $_.RetrieveDasAdvancedRuntimeInfo()).HeartbeatDatastoreInfo | %{
                $hbDatastores += $_.Datastore
              }
            }
            $hbDatastores -notcontains $ds.ExtensionData.MoRef
          }
          else{$true}
        }
        # No vdSW file
        NovdSwFile = &{
          New-PSDrive -Location $ds -Name ds -PSProvider VimDatastore -Root '\' | Out-Null
          $result = Get-ChildItem -Path ds:\ -Recurse |
          where {$_.Name -match '.dvsData'}
          Remove-PSDrive -Name ds -Confirm:$false
          if($result){$false}else{$true}
        }
        # No scratch partition
        NoScratchPartition = &{
          $result = $true
          $ds.ExtensionData.Host | %{Get-View $_.Key} | %{
            $diagSys = Get-View $_.ConfigManager.DiagnosticSystem
            $dsDisks = $ds.ExtensionData.Info.Vmfs.Extent | %{$_.DiskName}
            if($dsDisk -contains $diagSys.ActivePartition.Id.DiskName){
              $result = $false
            }
          }
          $result
        }
      }
    }
  }
}

Annotations

Line 24-26: A simple Object By Name implementation. It allows to pass the datastores by name or by object to the function.

Line 27: The parent of the datastore is used in a couple of tests further on in the script

Line 31: Test if there are any VMs or Templates present on the datastore

Line 33: Test if the datastore belongs to a Storage Cluster

Line 35-40: Test if the datastore is managed by Storage DRS. The Enabled property in the StorageDrsPodConfigInfo object is used as the indicator.

Line 42: Test if SIOC is enabled for the datastore

Line 44-57: Test if the datastore is one of the Heartbeat Datastores. The test first gets all the clusters known in vCenter and then filters out those clusters that have hosts on which the datastore is visible.

Line 48,56: If the host is not part of a cluster, the HA heartbeat test is considered as successful.

Line 59-65: Test to see if the is a Distributed Virtual Switch configuration file present on the datastore.

Line 67-77: Test if the datastore is used as a scratch partition.

Sample usage

The function can be used in a stand-alone or in a pipeline construct.

Get-DatastoreUnmountStatus -Datastore DS1

The pipeline construct could look like this

Get-Datastore DS* | Get-DatastoreUnmountStatus

The function produces 1 object per datastore. Each of the properties in the object represents 1 test that the function executes. Something like this.

The output shows us that we will probably not be able to unmount datastore DS1, because:

• the datastore is part of a Datastore Cluster
• the datastore is managed by Storage DRS
• there are VMs (or Templates) on the datastore
• the datastore is used by the Datastore Heartbeat
• the datastore has SIOC enabled

The functions to solve this and allow an unmount of the datastore will follow in some future posts.

Enjoy !