Upload & Sell: Off
consider looking at how much live storage you need at all times, that is, how many TB do you need spinning every time your computer is on. the more storage you need live, the more costly the solution.
lets say you want 8TB live with two backups. You will need a RAID array of some sort because there are no 8TB drives, and then you will need another one for the backup solution because again there's no 8TB drives.
The backup would be turned on as needed and a second one would be offsite.
You can guess this is very expensive already, but you're entering small business solutions territory.
Folks run this way with a network storage server for live storage instead of attached to a single PC as it can get expanded easier and there are some other benefits.
You can save on the live storage solution by paring it down and using drives as 'tapes', sorted maybe by year, and plugging in only the year you need. lightroom has a way to access hard drives that are offline as you connect them from what i recall.
the backups can be done cheaply by just having duplicate/triplicate copy of each drive on identical drives.
Problem is mainly in the amount of data you are using and you are outgrowing single HD sizes available today. From what I can gather you can either:
-use less data so you can fit on single HDD sizes
-use a filing system with 2/3/4TB HDDs whichever are economical, as 'tapes' sorted by year and/or data type-music/video/etc
-spend money on a raid solution with backups. backups being the pricey bit. consider tape backups?
-? ? ?