Storage Capacity Runout change in behaviour

We encountered an instance where the usage of a SAN dramatically changed and it filled up in very quickly and caught people off guard.

So I have created various views, Usage Freespace % graphs and the Storage Capacity report.

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Alas it appears I can not turn the runout time in to a graph I had hoped to be able to do that and use that as a basis for an alert as alerts on a SAN hitting x capacity is one thing but what the business has asked is whether it is possible to alert on a dramatic change in behaviour to the expected runout date to give an immediate alert. Ie a change of gradient as it were and a heads up. A sustained drop in freespace % over time would be the same thing I guess.

I see SRM.StorageArrays contains the following fields:CapacityRunoutSlope, CapacityRunoutOffset,CapacityRunout and CapacityRunoutDate but it seems to be a current value only, not historic records.

Has anyone thought of this before and any advice?

Thanks in advance