Storage Requirements - Help

Hello All.

I am looking to buy a storage device from Dell, but need your help in confirming that the model I selected is ok and hopefully score some points from you on the correct configuration to have. I have a storage device with 6TB data on it and need to come up with its replacement. The device is accessed by 250 users who can backup their data and share files via the pre-created shares. the current backup system is manual and will be changed to an automated system running BE2014 for all users. We are planning to give each user backup space totalling 20Gb plus we would like to retain 5GB per person for the document share space. My LAN speed is 10/100/1000 so data transfer speeds are good. My environment has R710 servers running on Server 2008 soon to be Server 2012 R2.

I selected either the MD1200 or the MD1400 as I was looking for expansion abilities and capacity to carry many drives. The challenge I have now is knowing of compatibility with my model server (it may be from the same manufacturer but may not work), if the solution can work with BE2014 as it is known that some hardware solutions lack compatibility with software solutions, if there are other drive options outside of those listed as being available for the server (4TB or any such drives).

Please help.