They are using ZFS, scrubbing is one command.

zpool scrub

(This may be a myth: It's not something you should actually do that often because actually reading the media may dregrade it.)

or for btrfs users out there:

btrfs scrub start /mnt/volume_name

Either way, it'd be fine on SSDs, then?

Hm? As long as the error correction technology on your chosen SSD of choice stands up, I guess... yes? What, exactly, are you asking?

My thought was "reading SSDs doesn't degrade them, so there's no disadvantage to constant scrubbing." Unless I've misunderstood what you mean by "reading."

Ah, right, fair point. AFAIUI SSD storage does degrade a tiny(!) amount when reading, but magnetic storage degrades quite a bit more.

(That's where that came from, draw your own conlusions :).)