I'd be curious what their RAID is setup. I agree and run ZFS for our data storage.

Check out https://www.digitalocean.com/community/questions/how-did-do-... for your answer. It's a bit old, but still true.

Is it single RAID controller or is there a redundant setup?

Anecdotally: Every company I've worked for that uses hardware raid controllers, it feels like the controllers break about as often as one of the disks. Sure, still an improvement over no RAID, but still ridiculous compared to any decent software raid (md or ZFS).

You lose a RAID card as often as spinning metal disks? Sure that's not a wild exaggeration? Sure sounds like one. In 15+ years of doing this, I've only been a part of a RAID card swap three times. Once was just to be safe with an overly paranoid customer.

That said, I'm a fan of moving away from RAID. It's just more complexity in the face of a movement towards simpler architectures. The one benefit of a good RAID card: stupid fast, safe writes with a BBWC.

It may be. As I said, "it feels like" - I'm probably assigning some selective memory bias because when it does happen it's much more of a pain.