I purchased 3 Drobos a few years ago, and had 10 years of photographs stored on two Drobo 5Ds. Drobo uses a proprietary software that failed when the 5D required a new drive with larger memory. This happened the first week of December last year. I had just copied 8TB of files from the first Drobo to the second Drobo. Within minutes both drives failed. The files were locked, and I had to contact Drobo and pay them to open a case. Over the course of the year Drobo had me run test after test on the drives, and responded with multiple software updates to try to access the information. I made phone call after phone call to the company to gain access to my files. The last software update they wrote for my Drobo 5D brought the drives back, but didn't get my Drobo to mount, which meant I could not access the information. I pleaded with them to send in my drive pack so they could retrieve the information. They refused. I made calls to several of their recommended companies for data retrieval, but they average cost to do this was $7000.00. Yes $7000.00. Drobo offered $300 off a new Drobo to rectify the situation. That is not only a joke, but an insult. So here I am, stuck with 3 locked Drobos. I recommend looking elsewhere for storage solutions as Drobo has been an inferior product in my opinion.
Read about other Drobo experiences:
http://boards.straightdope.com/sdmb/showthread.php?t=507208
http://forum.luminous-landscape.com/index.php?topic=38936
https://www.youtube.com/watch?v=uz-jfAvtKAI
https://forums.plex.tv/discussion/47900/thinking-of-buying-a-drobo