I am the technical architect for the Diagnostic Imaging solution for a number of National Health Service Trusts in the south of England. Currently, to provide the imaging for CT, MRI, a bit of cardio and a whole lot of plain xray and ultrasound, we have an archive of about 300TB of data. Replicated, and with local caching that is about 1PB of deployed storage. I am paying heavily for a second site replication, old school kind of solution, and it really doesn't scale well. Now I am looking at adding Digital Pathology to the shared imaging solution, and I really don't think that having two data centres growing to keep an online second copy of all of that data is viable; not least due to the cost of electricity of keeping a second copy spinning.
So, alternatives to this are:
Keep a second copy in the 'Cloud'. No clue on what my RTO would be.
Tape: Defined RTO, RPO, mostly passive means I don't have to worry too much about power consumption. I can keep multiple generations of data on tape if so required. My existing applications support Information Lifecycle Management and Online/Nearline/Offline storage heirarchies
Why would I NOT want a high density tape store as part of my solution?