Full frame rate (30fps)? 24/7?
If so, you will need much more storage.
What is the application?
are all these cameras in one location or multiple? what kind of network and connectivity are provisioned? what kind of features are required for the backed up data and how frequently will it be accessed?
I have a system with a similar build to this!
Main Unit - Lenovo Thinkserver RD650 (70D00025UX)
Attached Storage - ThinkServer SA120 (no model number on me, sorry)
RAID Card - LSI9280-8e 6Gb SAS RAID
Extra CPU - Intel Xeon E5-2630 v3 (8-core)
Extra Memory - 3x 8GB stick, 16GB storage for each
Operating System - Windows Server 2012 R2
Hard Drives - 6TB WD Se drives, SATA for the main unit, 4TB SAS for the DAS
Multiple servers can be used to decrease some costs, but this will give you a good handle on the build.
Luxriot also builds their own servers if you live in the US. The warranty seems to be reasonable.
As you are using Luxriot SW, I assume that you already have used their online calculator regarding minimum technical requirements.
I understand that the main problem is the storage capacity. There are several manufacturers of multiple HDD rackmount cabinets with room for more than enough HDDs.
Here you have some companies using such cabinets:
You can get cabinets like these from manufacturers in Taiwan and China. Focus on the swap bay cabinets.
I'll leave you more info on your Company facebook profile.
Rgds from a non-luxriot user in Norway