######################
# Storage vMotions VM files from one datastore to another, ie. from NetApp to NexSAN
######################

## Must have VMWare PowerCLI 6+ installed
Add-PSSnapin "VMware.VimAutomation.Core" 


######################
# Function block     #
######################
function cenWriteLog ($Message, $NewFile)
{
    $DateTimeStamp =  Get-Date  -Format "yyyy-MM-dd HH:mm:ss"
    $DateTimeStamp = "** $DateTimeStamp  **"
    if ($NewFile)
    {
        $DateTimeStamp | out-file "log.txt"
    }
    else
    {
      $DateTimeStamp | out-file "log.txt" -Append  
    }

    $Message | out-file "log.txt" -Append
    $DateTimeStamp
    $Message
} #Endfunction cenWriteLog
######################
# Function block end #
######################


######################
# Main script        #
######################
#Disaster Recovery control variables
$VC_Server = "Target vCentre server" 
$VM_LOCATION = 'Example folder name ' #VC folder to look in
$DS_SOURCE_FILTER ="Snap*" #source DataStore location, use wild cards to scan more than one datastore
$DS_TARGET_FILTER_PRIMARY = '*nexsan*sas*' #Primary target DataStore, accepts wildcards
$DS_TARGET_FILTER_SECONDARY = '*nexsan*sata*' #Secondary target DataStor, accepts wildcards

#Process control variables
$TASK_MAX = 1 #Maximum number of VC tasks that can execute, due to the preformance of the storage subsystem, max recommended value is 3
$TASK_WAIT = 1 #Delay between retrys in minutes
$VM_MOVE_ASYNC = $true #$true for async, $false for sync.  To force one svmotion at a time, set this to $false
$DS_BUFFER = 200 #Datastore space (GB) to remain free after SVMotion


CLS
cenWriteLog -Message "Scripted SVMotion started" -NewFile $true

#Connect to VCenter
$ResultText = Connect-viserver -Server $VC_Server 
cenWriteLog -Message $ResultText


$FoundVMs  = Get-VM -Datastore $DS_SOURCE_FILTER |WHERE {($_.Folder -like $VM_LOCATION )} |SELECT Name, UsedSpaceGB
cenWriteLog -Message $FoundVMs

foreach($VM in $FoundVMs)
{
    #record VM details
    $VMName = $VM.Name
    $RequiredSpace = $VM.UsedSpaceGB + $DS_BUFFER

    [boolean] $VM_Relocate = $false #Flag to monitor the status of the operation

    #Get primary datastores
    $DataStore = Get-Datastore -Name $DS_TARGET_FILTER_PRIMARY |WHERE {$_.FreeSpaceGB -ge $RequiredSpace} |SELECT Name | SELECT -First 1

    #if a suitable datastore has been found
    if($DataStore)
    {
           
        $TargetDSName  = $DataStore.Name   
        $VM_Relocate = $true

    } #if
    else
    {
        #Get secondary datastores
        $DataStore = Get-Datastore -Name $DS_TARGET_FILTER_SECONDARY |WHERE {$_.FreeSpaceGB -ge $RequiredSpace} |SELECT Name | SELECT -First 1

        if($DataStore)
        {  
            $TargetDSName  = $DataStore.Name    
            $VM_Relocate = $true

         } #if
        
    }
    if ($VM_Relocate)
    {

        $SleepCOunt = 0
        do
        {
                    
            #Increase the sleep time to prevent querying the VC server too often
            $SleepCount++
                    
            #Get current task stats
            $Task_Queued = Get-Task -Status:Queued
            $Task_Running = Get-Task -Status:Running
            $TaskCount = 0

            #Count the number of tasks currently running, sleep for a few seconds/minutes if applicable in order to reduce load on the server
            if ($Task_Queued) {$TaskCount = $Task_Queued.Count}
            if ($Task_Running){$TaskCount += $Task_Running.Count}
            if ($TaskCount -ge $TASK_MAX) 
            {
                $SleepTime = ($TASK_WAIT * $SleepCount)
                cenWriteLog -Message "Sleeping for $SleepTime minutes, task count $TaskCount"
                Start-Sleep -Seconds ($SleepTime * 60)
            }
        } while ($TaskCount -ge $TASK_MAX) 

        cenWriteLog -Message "Moving $VMName"
        Move-VM -VM $VMName -Datastore $TargetDSName -RunAsync:$VM_MOVE_ASYNC
    }
    else
    {
        cenWriteLog -Message "Unable to move $VMName"
    }

    
} #for..each

Disconnect-VIServer -Server "Target vCentre Server" -Confirm:$false
######################
# Main script end   #
######################