1. A method of placing workloads in a multi-array system comprising a plurality of storage arrays, the method comprising: determining, for each of a plurality of storage arrays, a current system activity level trend of the storage array using a centralized component within the multi-array system, by periodically monitoring a plurality of performance metrics and determining the rate at which each monitored performance metric is changing over time; receiving a performance profile of a workload to be executed on one of the storage arrays; generating, for each of the plurality of storage arrays in dependence upon the current system activity level trend of the storage array and the performance profile of the workload, a projected system activity level trend for the storage array, wherein the projected system activity level trend identifies an expected impact to the performance metrics of the storage array created by placing the workload on the storage array; wherein generating the performance profile of the workload to be executed on one of the storage arrays further comprises receiving user input identifying the type of application supported by executing the workload; identifying, in dependence upon the projected system activity level trend for each of the plurality of storage arrays, an optimal storage array for receiving the workload; the optimal storage array is found by generating a score for each storage array based on trend and availability of storage and processor cycle that can be used as an indication of how well a particular storage array can support a particular workload; the optimal storage array has the lowest score and has sufficient resources to support the workload for the longest period of time; placing the workload on the optimal storage array.