There are some alternatives to Data Domain for this use case when the customer’s backup workload will not benefit from deduplication (ex: video). In these situations, Data Domain becomes far less effective driving up its effective $/GB cost. Isilon is a more attractive solution in this case as a simple scale out content repository.
The Spiderchart below shows the design characteristics of the platform(s) in relation to the workload requirements. Note overall alignment and relative strengths related to the target workload.