External RAID storage?

It's hard to beat OWC's RAID solutions. Visit their website at www.macsales.com, they specialize in Macs and everything they sell works well and is competitively priced.

 

Backup redundancy is several backup drives "Not" in Raid - i.e. not connected together.
Raid 1 is nice for copies when all is well, but it can also copy a bad problem across the set.

Here's a thought - one of many on the subject
https://www.backblaze.com/blog/the-3-2-1-backup-strategy/

 

I have been successfully using an Onnto DataTale quad interface, and now I have bought the USB3 version.

These can be had for a very good price, but not from many places. There's also a more expensive TB version, but still very competitive.

I chose them because they support 1+0, can be flexibly configured as multiple volumes, and can be managed by software, and a reconfiguration password set (I avoid RAID enclosures that are only managed by buttons).

I think the speed is OK.

What you will not be able to do is grow a volume after it has been created. For this you need something a lot more expensive, like Areca.

 

I have one of these which I populated with 4 x 3TB HGST Deskstar NAS HDDs to give me a RAID5 volume of 9TB. These are G-Tech (part of HGST) brand and work very well. You can put up to 4 x 6TB into them, giving you up to 18TB in RAID5 storage. Bear in mind, you need to put 4 drives of the exact same make/size in them.

http://eshop.macsales.com/item/MISC/0G033S2TB0GB/