Storage Spaces helps protect your data from drive failures and extend storage over time as you add drives to your PC. You can use Storage Spaces to group two or more drives together in a storage pool and then use capacity from that pool to create virtual drives called storage spaces. These storage spaces typically store two copies of your data so if one of your drives fails, you still have an intact copy of your data. If you run low on capacity, just add more drives to the storage pool.
I use this as part of my Household backups.
Tips
Recover space if wildly out from expectations.
Run this in PowerShell Admin
Optimize-Volume -DriveLetter S -Verbose
Drives not enabling
Check the USB ports are not being shut down to save power.