Redundancy possible between pools on Synology DS218?

[tabl]

I have a 2 bay nas with one 4tb SSD (pool 1) and one 4tb HDD (pool 2).

How do I mirror the two pools for redundancy?

Detail: one of my WD SSD's failed and has been at WD for over 6 weeks without any communication from WD.

Out of caution, I purchased a 4tb IronWolf HDD since I have absolutely no idea if WD is ever going to communicate about my RMA, and I didn't want to drop another $500 for a SSD, instead I got the same size HDD.

The HD was initialized in a different pool than the SDD (I understand this is normal with SSD/HDD combos).

Now I'm wondering if/how I can mirror the two pools for redundancy.

Any ideas?

Thanks!

FYI WD is a failed company, never buying their junk again!

 

[Rusty]

You can backup, you can snapshot but you cant have 2 separate pools in a redundancy the same way as you have redundant drives in a single pool/volume.

So backup, snaps, or even folder sync is possible but that's about it.

 

[Telos]

And the obligatory comment, that true backup is off-NAS. (external drive, cloud service, second NAS (ideally remote).

What is 3-2-1 backup?