<<Not necessarily Steve.  He is asking about UPS capacity and not power
supply capacity.  I think we don't know enough about the configuration
at this point to determine whether the UPS will have enough capacity
to back this system up in the event of a power failure.

We need a description of the configuration that is running off the UPS
including how many cards/disks/tapedrives are installed on the system.>>

I guess I don't see why. Based on the ratings of the devices discussed,
the effect of replacing "N" C3010-type drives with (2*N) ST15150-type
drives should be about zero in terms of power requirements. If the
"before" and "after" configurations have the same power demand (i.e.
assuming that the net change is exactly zero), I don't see what
difference it makes what else is in the box, or whether the power is
being supplied by a power supply, a UPS, five thousand white mice linked
to an alternator, etc. IOW, if the net change in power demand is zero,
the "after" system should be able to do anything the "before" system can
do. Perhaps more germane to the question asked, under the same load, the
UPS will have the same run time, independently of how that load is
divided up inside the box.

As an aside, the original question did not contain the phrase "back up",
so I'm not sure exactly what that means in this context.

Steve