Hi,
I was in need of errors against those lun's from the Storage Array.Does you storage have any cmd line utility which will help us to filter out errors/events logging against that lun during back_up time?
If you still have slots available in your HP array,i would suggest you to go ahead and push one new disk,carve out a lun and present the same,later move forward with the SV motion to HP datastore which is newly created.If you cant do that,still would like to know whats going wrong? we may have to do some test like sending few I/Os to the lun and capturing the ingress/outgress traffic from the Switch/Storage which will certainly let us know where the delay is happening.