Windows Server Failover Clusters

If this same scenario targets a Windows Server Failover Cluster (WSFC) much of the process is still the same for detecting signature collisions. The difference comes in when a new disk is connected and has a signature that is recognized by the Cluster Disk Driver it will place this new disk in a Reserved state which signifies the WSFC owns this disk and will handle the overall management (Initialization, Online, Offline). The screenshot below shows what this looks like from Windows Disk Management, notice the Reserved under each of the Disk IDs. This applies to disks that have either been previously added or are new to a WSFC.

In the event a new disk is connected which was created from a snapshot that was created from an existing disk on the same WSFC there will be a detected signature collision; remember the example of Volume 1 and Snapshot 1. The same collision logic described earlier will be used but the WSFC will not re-signature the new disk automatically like the standalone server. The WSFC will connect the disk and place it in an Offline state.

This is done to protect against having two disks with the same signatures which could cause corruption issues. Now even though this disk has been connected to the WSFC node it cannot be used until it has a new unique identification (aka signature). In order to use this disk in the WSFC you need to connect it to a secondary server or virtual machine outside of the desired WSFC and update the unique identification.

Before setting a new unique identification the volume on the FlashArray needs to be disconnected from the existing Host Group and connected to a different Host. Once that is completed you can use either of the methods below to accomplish this task.

Assigning a New Unique Id

DiskPart

This example show changing an MBR disk.

DISKPART> list disk
  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          150 GB      0 B
  Disk 1    Online         2048 GB      0 B        *
  Disk 2    Online         6144 GB      0 B        *
  Disk 3    Reserved       4096 GB      0 B        *
  Disk 4    Online         1024 GB      0 B        *
  Disk 5    Reserved       4096 GB      0 B        *
  
DISKPART> select disk 5

Disk 5 is now the selected disk.

DISKPART> unique disk

Disk ID: {C81F4AE3-967F-4D82-973A-448BD94888D9}

DISKPART>

Screenshot of what this looks likes from a cmd prompt.

Windows PowerShell

This example shows changing a GPT disk. You will notice that the below script is just automating DiskPart. This method will work with Windows Server 2008, 2008 R2 (Service Pack 1), 2012, 2012 R2 and 2016.

$guid = [GUID]::NewGuid()
$connecthost = $env:COMPUTERNAME
$uniqueIds = Invoke-Command -Computername $connecthost {Get-Disk}

ForEach ($uniqueId in $uniqueIds)
{
    If ($uniqueId.FriendlyName -like "PURE FlashArray*") 
    {
        $disknumber = $uniqueId.Number
        $cmds = "`"SELECT DISK $disknumber`"",           
                "`"UNIQUEID DISK ID=$guid`""          
        $scriptblock = [string]::Join(",",$cmds)
        $diskpart =$ExecutionContext.InvokeCommand.NewScriptBlock("$scriptblock | DISKPART")        
        Invoke-Command -ComputerName $connecthost -ScriptBlock $diskpart
    }
}

Once the signature of the disk has been changed the volume can then be connected back to the Host Group which is being used for the Windows Server Failover Cluster.