Wrong numbers at Pool response times with Netapp E-Series?

Hi,

I configured a Netapp E-Series 5600 in stor2rrd, but the pool response times look like strange. I have values between 46ms and 166ms. If I look at the values for volume response times, they are between 1ms and 9ms. Why is there such huge difference? Maybe the scaling is wrong, or is it summarising the volume response times? How is it measured?

Thanks