-----Bill Evans wrote: ----- >Some things I can figure out, like it will require 30+ minimum >scratch tapes per night (typically we run with 5). And each >collation group will have its own 'filling' tape. Other than the >extra library slots, are there any other things I haven't thought >of that will increase my h/w costs or administration time?
If you are planning for collocation by filespace for a copy storage pool with volumes shipped to an offsite vault, your are correct about the 30+ scratch tapes per night. In addition, I think your offsite reclamation processing will end up moving far more data, settling for a much lower average tape occupancy, or some compromise between the two. If you are only planning for collocation of a primary storage pool that stays in the tape library, I don't think you will need 30+ scratch tapes per night. When the configuration change is first made there will be an initial surge in demand for scratch tapes in order to provide each collocation group with its own filling volume. After that I would expect, on average, five collocation groups to need scratch tapes each night. The variability in the consumption of scratch tapes will be greater than it is now. The storage pool might, for example, need seven scratch tapes one night and three the next night, rather than five each night.