Unfortunately my english is only acquired, so I can not follow you exactly.
a) RAID is RAID and not a backup. With RAID you just have redundancy on the disks which is ok but in my opinion not a insurance to not do backups. Since RAID we use both, as RAID protects you from single disk failures, but can not help you go back in time or recover something you lost, eg. out of your courses, so RAID and Backup are complementary features
b) network-speed and network-performace is something else. I can not imagine a university campus lacking network-speed/performance
c) server-performance is another issue
d) server-redundancy and availability, tipically high-availability, implies a server-cluster with failover techniques which is another space to investigate and work on. We made such an experience with a high-available server-cluster with automatic failover, but lost a lot of performance, whilst from 2004 to 2012 I run a simple Moodle-Server with no failover enjoying a lot of performance, roughly 5000 courses, 800 GB of data. With traditional course and system backups as explained before
So if you want to serve/stream big big files to a lot of people concurrently, eg. like on youtube, you have to make a completely other design. But if you are talking about ONE big file to be serverd to 50 concurrent students, I guess your server AND your network is still ok, and no problem for Moodle either. There are Moodle-Performance-figures if you need to lookup numbers. Simply search for Moodle Performance. Such figures are also included in the server prerequisites before you start installing Moodle.
Rosario