Is there a recommended storage level percentage for optimum performance / cost ?
Obviously I realise there are lots of factors to take into consideration, such as projected growth, disk sizes / arms, I/O etc.
But with all these catered for should I be looking at something around 75% or say 50%?
50% would seem low to me and that I will have a lot of moneys’ worth of Disk sitting round doing nothing, 90% would seem high with little room to react if there were issues. I am trying to identify a band say 70 - 85% where the ideal level of utilisation should sit so I can convince my users there is no issue with us being at 85% but also to convince my purse holders that we need to by more when we start getting towards 90%. Taking into consideration the system husbandry is maintained.
It’s not just about cost and forward planning but also about convincing them that seeing disk at 85% is not going to cause any issues in performance, given that the page faults are within the tolerances recommended by IBM.
I know it’s a vague question but you guys have a vast of experience and I am asking for your views or IBMs if indeed they have one.
Software/Hardware used: V5R4, V6R1, Power 5's, 6's and 7's