Check server before starting service

I need to edit a script. There is a service that is on two Windows Server 2008 R2. They are load balanced. I need it so when I run the script that starts the service on the primary server and the secondary, so before it even start the service on both servers, the goes out and checks to ensure the primary server is up and running, then continues on as normal to start the services on both servers.

# Start Appian
function StartAppian {
  $APNSVC = Get-Service -Name $AppianService

  if (!$APNSVC) {
    Write-Host "Appian Service does not exist"
    return
  }
  # Check to see if Appian's service is already started
  if ($APNSVC.Status -eq "Running") {
    if ($LB) {
      if ($MULEAPNSVC.Status -eq "Running") {
        Write-Host "Appian Service on the Load Balanced Server already is started!" -ForegroundColor Yellow
        return
      }
    }

    Write-Host "Appian Service already is started!" -ForegroundColor Yellow
    Read-Host "Press any key to return"
    return
  }

  # Check if DEV's Process Design has a writing_*.kdb file and delete it
  if ($Server -eq "DEV") {
    #gw1
    if (Test-Path $APPIAN_HOME\server\process\design\gw1\writing_*.kdb) {
      Write-Host "Removing writing_*.kdb from GW1" -ForegroundColor Yellow
      Remove-Item $APPIAN_HOME\server\process\design\gw1\writing_*.kdb
    }
    #gw2
    if (Test-Path $APPIAN_HOME\server\process\design\gw2\writing_*.kdb) {
      Write-Host "Removing writing_*.kdb from GW2" -ForegroundColor Yellow
      Remove-Item $APPIAN_HOME\server\process\design\gw2\writing_*.kdb
    }
  }
  Write-Host "Starting Appian"

  # Place the name of the service here to start for Appian
  Start-Service $AppianService
  Notify("StartAppian")
  if ($LB) {
    (Get-Service $MULEAPNSVC.Name -ComputerName $MULE).Start()
    Write-Host "Starting Mule's Appian" -ForegroundColor Magenta
  }

  cmd.exe "/C $APPIAN_HOME\server\_scripts\diagnostic\checkengine.bat -s >    $logdir\Startup.log"

  # These lines check the Startup log for fatals and errors at the beginning
  $fatals = Select-String FATAL $logdir\Startup.log
  $errs = Select-String ERROR $logdir\Startup.log

  # Check for errors and fatals again
  $fatals = Select-String FATAL $logdir\Startup.log
  $errs = Select-String ERROR $logdir\Startup.log

  Write-Host "Still warnings or Errors in CE" -ForegroundColor Yellow
  # Increment times
  $times = $times + 1

  # If times > threshold, email out error message
  if ($times -gt $threshold) {
    SendAlert("There is a problem with Appian - It won't start")
    Write-Host "There was a problem with Appian..it took too long to start -  emailing alert" -ForegroundColor Red
    Read-Host "Press any key to exit"
  }
}
Write-Host "Appian Started" -ForegroundColor Green
Read-Host "Press any key to return"
}

You can do that with a simple Test-Connection at the start of the script.

if ($ping = Test-Connection -ComputerName PrimaryServerName -Quiet) {
Write-Host "Host avalible"
}

else {
Write-Host "Host unavalible"
Exit
}