right now i finally got all 15 of my usb miners running via pi but using 4 hubs in total, 3 dlink 5ports and 1 roswell 10 port.  I have the one dlink as the main hub for the other usb hubs to plug into.  After trying and trying i could never get all 5 slots in both of the (dlinks dhub7 the popular one for pi) to every get all of the miners running.  I wasnt even close with cgminer so i switched to bfgminer.  So i offloaded 1 by 1 and in different setups took miners from the hubs and added them to the 5 miners i had in the roswell, i got to the max for the roswell, and then added some to the main dlink usb hub that plugs into my pi.  I am now stable with very very few HW errors ~1% down from 10%+.  

My question is there any other efficient way to run this. As i see it just get another roswell cause i cant link these dlinks to a main dlink hub for shit, anyone know the trick?  My cooling is powered outside the setup so thats not eating power.  Hate having 2 hubs here with only 2 miners in them, and if i put more in...magical HW errors.