http://en.community.dell.com/techcenter/performance-monitoring/foglight-administrators/f/4788/t/19557614#60975

This should assist you.

So did he add that code to the conditions of the rule?  I know practically nothing about groovy and syntax.  So if the name has npwgp in it, that will be true?  No idea what the BigDecimal is or if it's needed, the bottom part is what is in my copied rule. 

try{

BigDecimal bd = new  BigDecimal(#capacityAvailable from $scope.hostLogicalDisk#.toString());

availbility = bd.setScale(2,BigDecimal.ROUND_HALF_UP);

if(scope.get("virtualMachine").get("name").substring(0,8)!='npwgp')

{

if(availbility<=registry("VMWGaz vmLogicalDrive.fatal")) return true;

else return false;

}

else return false;

} catch (Exception e) {return false;}

-------------------------------------------------------------------------------------------------------------

if(scope.get("localState") <= 4)

{

try{

qObjs = #totalSpace from $scope.hostLogicalDisk#;

tmpList = qObjs?.values(qObjs?.topologyObjects[0]);

if(tmpList==null || tmpList?.size() == 0) {

          return false;

}

timeToFill = VMwareGetTimeToFull(#spaceUsed from $scope.hostLogicalDisk  for 7 days 1 day ago#,tmpList.get(0)?.getValue()?.getAvg());

if(timeToFill==null) return false;

@rulette_data["TimeToFill"] = timeToFill;

if((timeToFill!=0) && (timeToFill < registry("VMW:noOfDays.fatal"))) return true;

else return false;

}

catch (Exception e) {return false;}

}

return false;