I don't believe we collec that counter. Certainly not on pool level.
Unfortunately I'm not intimately familiar with ONTAP counters, but this sounds like it could be part of Adaptive QOS, wich works on flexvol level. I believe we have made some recent improvments in OCI to support Adaptive QOS, but since I don't really know if perfromance guarantees are a part of that and if they are if we really collect the necessary information with OCI, I'm a bit hesitant to say something that may turn out not to be true. I'm pretty sure we can't model this on pool level though.